A day after a gas leak forced hundreds of Alamo residents and employees to evacuate their homes and businesses, Contra Costa County officials were left to explain why an evacuation order went out to more people than necessary, and PG&E officials questioned why a crew was using equipment to dig.

The leak happened Wednesday when an East Bay Municipal Utility District crew hit a gas line while working with a backhoe when they'd been advised to use their hands, a PG&E spokesman said. The leak, at 3195 Danville Blvd., near Stone Valley Road, shut down neighboring streets and created additional traffic on Interstate 680.

According to multiple agencies, only residents and businesses within a 3-square-block area of the leak were affected. But text alerts went to parts of the county not affected and told people to leave the county during the evacuation.

Contra Costa County Supervisor Candace Andersen said Thursday that the erroneous information was the result of an upgrade to the national Integrated Public Alert and Warning System. IPAWS exists to alert carriers nationwide of potential emergencies, Andersen said, and the system was upgraded recently, but the county was not alerted.

Thus the system in place was not the same as the one that alerted residents to the Chevron Refinery explosion and fire in Richmond last August.

"In any disaster, the communication that goes out to the public has to be as informative and accurate as it can be," Andersen said. "In this case, not so much."

Andersen said she's awaiting a report from officials explaining how the IPAWS system could be upgraded without the county being alerted. She did say that citizens who had signed up to receive the county's community warning system did receive accurate texts and updates.

Those alerted to leave the county were under the auspices of the IPAWS system, she said, a separate alert system that does not require people to register for alerts. To register for alerts, people can go to www.cococws.us, she said.

"More people were alerted and alarmed than needed to be," Andersen said. "But I would say that it's better to be alerted and alarmed and not need to be than the other way around."

The evacuation order was lifted at 3:30 p.m., just after PG&E crews sealed off the 1¿1/2-inch leak, company spokesman J.D. Guidi said. Crews completed repairs by 10 p.m., he said.

The EBMUD crew was in an area where PG&E and other gas lines are difficult to mark, Guidi said. The company uses technology to show crews where the gas lines run, but a weak signal caused the equipment not to work in the area, Guidi said.

"So at that point, we actually advised EBMUD to dig with their hands," Guidi said. "We don't know why they were using equipment."

Charles Hardy, a spokesman for EBMUD, said crews do not take instructions from PG&E on how to do their job.

Crews were out early Wednesday morning to repair a service line break in a small pipe on Danville Boulevard when they hit the gas line, Hardy said.

"(PG&E's) responsibility is to mark the street and tell us where the pipes are, not to tell us how to dig," Hardy said. "(PG&E) did not identify that there was a pipe in the area. We are not going to dig where there is a gas line."

No injuries were reported as a result of the leak.

Staff writer Katie Nelson contributed to this report. Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.