ALAMEDA -- A gas leak that sent four Encinal High School students to an area hospital and prompted an evacuation of the entire campus Tuesday morning was caused by a loose pipe fitting in a science classroom. An additional 10 students were evaluated and released to their parents.

The leak, which was reported at 8:48 a.m., prompted an evacuation of the entire campus at 210 Central Ave., said Susan Davis, an Alameda Unified School District spokeswoman.

A PG&E crew and Alameda firefighters allowed students and teachers to return to class at 9:32 a.m., although the school's science wing was temporarily closed so that the workers could check for other possible leaks.

The loose fitting was under a table, Davis said.

The school district is urging any students who feel ill after leaving school to have a parent or guardian call a doctor and then notify the Encinal office at 510-748-4023.

Reach Peter Hegarty at 510-748-1654 or follow him on Twitter.com/Peter_Hegarty