Gas Main Break Forces 80 People Out of Their Lake Forest Homes : Leak: Construction mishap on shoulder of northbound Interstate 5 ties up afternoon traffic.

An errant bulldozer broke a major underground gas pipe along Interstate 5 on Wednesday, causing traffic snarls and forcing the evacuation of nearby houses and apartments.

About 80 people were told to leave their homes just before 2 p.m. after a construction crew working on the freeway-widening project gashed a six-inch gas main next to the shoulder of the northbound lanes near the El Toro Road exit, Orange County Fire Authority spokesman Dan Young said.

“We secured the area and cleared the homes because there can be a real threat involved in a break of this magnitude, if an ignition source is found,” Young said.

One freeway lane and the El Toro Road on-ramp were closed well into the evening to make way for Southern California Gas Co. crews, the California Highway Patrol said.

Residents of the southeast buildings of the Timbers apartment complex spent the afternoon in the parking lot, awaiting permission to go inside. Some complained of fume-induced headaches and rattled nerves; others chatted with American Red Cross workers or lounged in lawn chairs.

“All you could hear was this hissing sound. It sounded like they were sand-blasting the side of the freeway,” resident Paul Kushner, 45, said.

The wind carried most of the noxious fumes toward the freeway, where drivers slowed to see the commotion.