Yellow-jacket swarm attacks fairgoers

(07-03) 13:55 PDT Pleasanton -- About 100 people were stung by yellow jackets at the Alameda County Fair on Friday night when the popular fireworks display apparently disturbed a nest and sent a swarm into the grandstands, according to the county Fire Department.

No one suffered a serious allergic reaction to the stings, said Alameda County Fire Department spokeswoman Aisha Knowles. Several people were stung multiple times, and victims ranged in age from a 6-month-old baby to an adult older than 60.

The wasp attacks began shortly after the fireworks show started at 9:15 p.m. About 5,000 people were in the grandstands, and 15 minutes later sting victims started showing up in the first aid area, Knowles said.

"Apparently there were a number of (yellow jackets) also in attendance for the fireworks display last night," Knowles said Saturday.

She said emergency personnel at the fair set up a triage area to care for those who were stung. Everyone was treated on site and there were no hospitalizations, Knowles said.

By midnight Friday, an exterminator located and removed a ground nest, Mitchell said. The yellow jackets were probably disturbed by the vibrations as the fireworks were launched, not the explosions overhead, she said.

The fair attracted attention Thursday after a chain on the Wacky Worm, a kiddie roller coaster ride, broke, injuring five children and two adults. One child and one adult were taken to Valley Care Hospital in Pleasanton for further observation. The others were treated at the fairgrounds.

The ride was repaired and reopened Friday afternoon.

E-mail the writers at eallday@sfchronicle.com and wkane@sfchronicle.com.

This article appeared on page C - 3 of the San Francisco Chronicle