SAN DIEGO >> Officials are investigating what may have caused 22 students to get sick after lunch at a San Diego elementary school.

San Diego fire spokesman Maurice Luque (loo-KAY’) says children at Audubon Elementary School had upset stomachs and some were throwing up after lunch Thursday.

Of the 22 that were sickened, 18 went to the hospital.

The affected students ranged from kindergarteners to seventh graders.

School officials suspect something the kids ate or drank is to blame, but haven’t determined what it may have been yet. County health officials are aiding in the investigation.

An initial check of the kitchen showed refrigerators are working and milk and juices are not expired.

The school’s meals are prepared off-site and delivered.

About 425 kids ate lunch Thursday at the year-round school.