Law enforcement officers converged on San Marcos High School near Goleta on Monday following a fireworks explosion that was heard on campus. (Paul Donohoe photo)

San Marcos High School was placed on lockdown Monday afternoon following a fireworks explosion that was heard on campus.

The incident occurred shortly after noon at the campus at 4750 Hollister Ave. near Goleta.

A tweet from the Santa Barbara Unified School District noted the locked down.

“Principal confirmed it was a firecracker,” the tweet said.

“There are no shots fired at San Marcos High School,” the Santa Barbara County Sheriff’s Department said in a tweet. “The incident was determined to be a firework. No one hurt, Everyone safe.”

At about 1:20 p.m. the school district tweeted that the lock-down had been lifted.

Investigation was underway to determine who is responsible, the Sheriff’s Department said. Anyone with information is asked to call 805.683.2724 or 805.681.4171 for anonymous tips.

San Marcos High has experienced recent incidents of threatening graffiti and online threats, prompting an increased law-enforcement presence on campus.

Check back with Noozhawk for updates to this story.

Noozhawk executive editor Tom Bolton can be reached at Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.