Update: Westbound lanes on Shaw Avenue have reopened to traffic.

Update: Eastbound lanes on Shaw Avenue have reopened to traffic. Westbound Shaw Avenue is still closed.

Update: PG&E spokesman Denny Boyles said the gas leak has been closed, but Shaw will remain closed while workers assess damage.

Westbound Shaw Avenue will be closed through mid-afternoon, with eastbound opening sooner.

A contractor punched through a large utility gas line in northeast Fresno early Friday, causing a major traffic and business disruption that will last until Saturday morning.

Shaw Avenue between First and Sixth streets was closed after the crew, which was doing what Pacific Gas & Electric spokesman Denny Boyles called "directional boring," hit the line, releasing natural gas. Boyles said the contractor, Atazz Technical Services from Sacramento, did not follow proper procedures or notify PG&E's "Call Before You Dig" service. The gas leak could be a costly one for Atazz, which was doing work for AT&T. Boyles said the company might be on the hook for revenue lost by businesses that were forced to close.

By 9 p.m. Friday, electric service had been returned to all but 11 customers, and PG&E estimated the flow of gas would be contained between midnight and 3 a.m., Boyles said. Once the flow of gas is stopped, PG&E will work with Fresno police and fire officials to reopen portions of Shaw Avenue, he said.

The break happened about 3 a.m. Friday. Firefighters, police officers and utility workers scrambled to the area and shut down Shaw. About 300 business owners along with some apartment residents were affected.

The closure of the busy thoroughfare caused a headache for drivers en route to Fresno State and others who use Shaw to travel between Fresno and Clovis. The power shutdown also caused some signal lights to go dark and others to flash red in all directions. As the gas streamed from the broken line, a Fresno police sergeant reminded officers not to light signal flares to help direct traffic.

City workers were also checking area sewer lines to ensure that they had not been damaged. Fresno Fire Department Chief Rob Brown said a quick response by emergency workers minimized the risk of the leak. He also stressed the importance of limiting access to the area.

Meanwhile, Fresno Fire Department spokesman Koby Johns had a message for people who work in the area: "Your business is closed. Don't even come to work."

Boyles said that repairing the leak would be time consuming because the punctured line was made of steel. Unlike plastic lines, steel must be welded. And after the line is repaired, PG&E workers will have to recheck every customer's outlets to ensure that they are safe. Adding to the difficulty, city workers will also have to check nearby sewer lines to see that they are OK.

View Broken gas line closes section of Shaw Ave. in Fresno in a larger map