I've spent many years studying and hunting 'Yotes so take this as you will.
Adult coyotes are typically solo hunters and usually only hunt in pairs when denning. It is very unusual and disconcerting when they run in a pack, especially one this large. Like all canines, they become emboldened when running in packs with an alpha, as these were. (We watched an alpha attack a young yote at the cooler). For more in depth info see Hope Rydens "God's Dog", the bible on canis latrans.
Excerpts from a Google search "coyote attacks on humans":
The California Department of Fish and Game estimates roughly one person gets bitten by a coyote per year in California. The last human to be killed by a coyote was a child in the Los Angeles area around 1980. (SDUT 1/3/95, B1; 5/16/00, B3)
For comparison, over 300 people have been killed by domestic dogs in the U.S. between 1979 and the late 1990s. (Humane Society of the U.S., reported in Tracking and the Art of Seeing, Paul Rezendes, second edition, 1999, p. 194)
From 1993 to 1997 there were seven coyote attacks on humans in Arizona, with over half in 1997. (SDUT 12/17/97, A3) "The best estimates assert that, in recorded history, there have been 20 to 30 coyote attacks on humans that resulted in injuries." (Tracking and the Art of Seeing, Paul Rezendes, second edition, 1999, p. 194)
Paul's summary is much lower than the total number derived from the previous estimates; perhaps the definition of injuries is different for his estimate. At one person per year in California, one would estimate ~10 attacks per year in the U.S., giving 500 attacks in the last 50 years alone.
1993. A coyote bit a Fallbrook, California boy as he slept on the deck of his home. (SDUT 1/3/95, B1)
7/20/95. Fifteen-month-old Erica Galvin of Reno, Nev., suffered seven puncture wounds to her right thigh when a coyote sneaked up on her about 4 p.m. Thursday near the merry-go-round and tennis courts at Griffith Park in Los Angeles. The coyote was scared away by her mother. (SDUT 7/24/95, A3)
6/13/96. A 3-year-old Palo Alto boy was attacked by a 2-year-old male coyote at the Windy Hills Open Space Preserve in Portola Valley, near Los Altos, CA. As the family was packing up the car after a picnic, the coyote used his teeth to grab the boy by the hand and drag him toward nearby bushes. The boy was playing with a Frisbee which was also bit by the coyote. The boy's 15-year-old brother scared away the coyote. The coyote was later trapped, and DNA testing (from the Frisbee) was attempted to make the id certain.
This was the first attack in the 25 year history of this Preserve. (Los Altos Town Crier 7/24/96)
10/96? (< 4/11/97). A 40-year-old woman jogger in Benkelman, Nebraska, was bitten on the leg when a coyote attacked her as she jogged around an athletic track. (Animal Damage Control Program of the USDA)
2/17/97. Lauren Bridges, a 40 pound, 4-year-old girl, was attacked by a 40 pound female coyote when she left her vacation rental on Saddle Road in South Lake Tahoe, CA. The coyote knocked her to the ground and began biting her face, the only part not covered by ski clothes. Her father heard her screams and pulled the coyote off his daughter as it continued ripping at her face with its teeth. Lauren required 22 stitches for 16 wounds to the girl's face, neck and scalp, out of a total of over 30 puncture wounds. One of the puncture wounds came within a centimeter of her jugular vein. The father was not bitten, and the coyote was killed moments later by a police officer. (Tahoe World region 2/24/97, 2/19/97 and 3/5/97)
In the previous month at South Lake Tahoe, Supervisor John Upton reported that a man was bitten by a coyote, other skiers were chased by coyotes, and children walking to school were followed by coyotes. Apparently, people had been feeding coyotes in the area, accustoming the coyotes to people. (Placerville Mountain Democrat 2/24/97)
4/97. Coyotes attacked and bit two Scottsdale, Arizona children in separate attacks within a week. Neither child was seriously hurt. (SDUT 12/17/97, A3)
12/10-11/97. On 12/10/97, a coyote attacked a 2-year-old boy in Tucson's Wildlife Ridge Park, but did not break his skin. The next day, in the same park, a 4-year-old boy was bitten and scratched and a 22-month-old toddler was bitten around her right eye and required seven stitches for the deep puncture wounds. (SDUT 12/17/97, A3)
7/29/98. There has been only one coyote attack on a human reported in Massachusetts in the past 50 years, on 3-year-old Daniel Neal of Sandwich while he was playing on his swing set. His mother forced the female coyote off Daniel, but the coyote hung around. Police responding to her call killed the coyote.
Daniel suffered puncture wounds and abrasions to the head, shoulders and back, but is OK. The same coyote had earlier chased a person on a bike and a jogger as well as chewing on a sleeping bag with a child inside. The first active coyote den on Cape Cod was found in 1985. In comparison, there are thousands of dog bites annually in Massachusetts. (Cape Cod Times 7/30/98; Environmental News Network, 8/5/98; Lexington Minuteman, 3/15/00)
1999. Seven people were bitten by coyotes between March and August in the Lake Tahoe area, including one tourist who was bitten in the thigh while walking in the Caesars Tahoe parking lot over Memorial Day weekend. Airplane flights at the South Lake Tahoe runway have been cancelled or delayed due to coyotes on the airport runway, who have even chased planes as they took off! In May, 1999, the airport was told by the FAA to find a solution to the problem. Animal control killed 19 of the boldest coyotes in the casino area. (SDUT 8/20/99, A28)
5/13/00. A 9-year-old boy was bitten in the buttocks by a possible coyote in a residential neighborhood in La Mesa, San Diego County, California. It was not 100% certain that the animal was a coyote. (SDUT 5/16/00, B3)
5/19/00. A 3-year-old boy was bitten on his side outside his Amaya Drive apartment complex at 7 pm in La Mesa, San Diego County. A responding police officer hit the coyote with a shotgun blast, but the coyote was not found in the next day. The boy was treated at Grossmont Hospital for four puncture wounds in his right side. (SDUT 5/21/00, B3)
10/02/01. Allison Newell, an 8-year-old girl and Luis Enrique Villalobos, a 7-year-old boy, were bitten by a coyote at 12:15 pm during the lunch hour at Truman Benedict Elementary School in San Clemente, California. The coyote bit the backpack of a third child. The coyote came into the lunch area and attacked Allison from behind. Fourth-grade teacher Mitch Colapinto threw water bottles and rocks at the coyote, which then ran through the playground and lunged at Luis. Both students suffered scratches and minor bite wounds, the girl on the back of her neck and the boy on his back and arm. They were treated at San Clemente Hospital and released. The treatment included beginning a series of rabies shots.
The school is surrounded by hillsides where homes are being built, destroying the natural habitat of the coyotes. Three coyotes were killed on a nearby hillside later in the day by wildlife specialists from the U.S. Department of Agriculture.
There have been a handful of other recent incidents in Northridge and Irvine. (LAT 10/3/01, B3, OCR 10/3/01)
LAT Los Angeles Times
OCR Orange County Register
SDUT is the San Diego Union Tribune