OAKLAND — A gas pipeline that ruptured and caused a fire in the Oakland hills Tuesday was cracked, a PG&E spokeswoman said Wednesday.

Spokeswoman Brittany Chord said there was a crack in the elbow of the 4-inch steel pipe, but it remains unclear what caused the crack and what ignited the fire.

The utility has sent the distribution pipe to an industry expert for further examination, Chord said.

The underground fire erupted at the intersection of Golf Links Road and Fontaine Street at 8:25 a.m., shooting flames through cracks in the street and prompting the evacuation of nearby homes. It burned for more than three hours until the line was capped at 11:40 a.m.

On Wednesday, PG&E brought in compressed natural gas tanks to deliver gas to nine customers while crews work to restore gas distribution to those homes.

The steel pipelines were laid in the area in 1946 and 1965, Chord said Tuesday. They were last surveyed in April 2012, she added, but surveyors were on the scene Tuesday, checking other pipes in the area.

Chord said that company officials typically survey pipes every five years, and that they have no particular concern at this point about other pipes in the area. If laid and maintained properly, pipes can last up to 100 years, she added.

The minor fire Tuesday caused some residents to recall a massive San Bruno explosion and fire in 2010; like Tuesday’s fire, that incident began in underground pipelines, though the pipes affected Tuesday were much smaller than the San Bruno line that ruptured. Eight people were killed and 38 homes destroyed in the San Bruno explosion and fire.

The gas main affected Tuesday was a distribution line that carries 40 to 50 pounds per square inch of gas, Oakland Fire Battalion Chief Lisa Baker said. The San Bruno explosion and fire involved a transmission line nearly 3 feet in diameter and carrying 300 pounds per square inch of gas, Chord said.

David DeBolt covers breaking news. Contact him in Richmond at 510-262-2728. Follow him at Twitter.com/daviddebolt.