SAN FRANCISCO — Ten students at a San Francisco middle school have been treated after ingesting an unknown substance that caused adverse reactions.

KTVU-TV reports that officials are looking into whether the students were sickened by marijuana edibles.

San Francisco Fire Department Lt. Jonathan Baxter said authorities received a 911 call at 1:20 p.m. from James Lick Middle School saying that students were experiencing “the effects of an ingested substance.”

Police and firefighters sent emergency vehicles and TV footage showed children being wheeled away on a stretcher.

San Francisco Unified School District spokeswoman Laura Dudnick said the school is working with officials to determine what happened. She could not say whether the students were sickened by marijuana.

The students’ ages were not immediately released.