Natural gas could be restored by Tuesday afternoon to the majority of 5,200 customers in Mandan who were without it Sunday, after workers repaired a leak in a pipe and began the process of switching off meters then relighting pilots in each home and business affected.

Montana-Dakota Utilities workers plan to work around the clock, individually lighting residents' and businesses' pilot lights.

The leak occurred shortly before 6 a.m. on Collins Avenue, just south of Division Street; a passerby reported a plume of gas accompanied by a strong odor.

About 35 homes were evacuated, and Sunday morning services at First Baptist Church were canceled. The leak was repaired by about 1:30 p.m.

Technicians also worked through Sunday afternoon and into the evening to shut off each customers' gas meters, which must be done before the pilot lights are re-lit; as of 8:30 p.m. Sunday, more than half of the affected area's meters were shut down. Gas can't begin flowing until all the meters are off.

Mark Hanson, spokesperson with MDU, said about 60 crews from a four-state area were working on the outage. If everything goes smoothly, he said, natural gas could be restored to a majority of the area by Tuesday.

Crews could come anytime during the night or day, and Hanson suggested households and businesses coordinate so someone is always available to let workers in.

"Residents may be getting a knock on the door in the middle of the night,"he said. He also suggested leaving phone numbers on the door if no one is available, so technicians can set up a time to return. He asked residents leave porch lights on to help technicians.

"We want to do this as quickly as possible,"he said.

The Red Cross set up a shelter in the Eagles Club on Collins Avenue in Mandan; as of Sunday night, about 10 people had checked in.

And by 8 p.m., the National Guard delivered more than 100 space heaters to the Mandan Fire Department for residents who want to stay in their homes; the heaters are on loan, said Tammy Lapp-Harris, Morton County emergency manager.

Lapp-Harris emphasized that residents should only use electric heat to stay warm, and not use charcoal or propane.

The Highway Patrol and Morton County Sheriff's Department offered extra law enforcement coverage during the process, and Lapp-Harris asked that residents check on their elderly neighbors.

Gov. John Hoeven authorized several state agencies to help the city, and addressed Mandan during a Sunday night news conference.

"We need coordination and cooperation with city residents,"he said, adding that they will continue to provide state resources to support the efforts.

Also attending the news conference were Mayor Ken LaMont, Lapp-Harris and representatives from the National Guard, the Red Cross and Mandan and Morton County officials.

As of Sunday evening, Mandan Public Schools and most area businesses planned to remain open. Officials had initially thought inmates at the Mandan jail would have to be relocated, but later decided that wasn't necessary.

Residents concerned about frozen pipes should keep heat flowing into areas with pipes, Lapp-Harris said, adding that more information on water pipes would be available this morning.

Forecasters said temperatures would remain mild through this afternoon, but predicted a frigid drop on Tuesday.

Vic Jensen, forecaster with the National Weather Service Bismarck office, said temperatures could drop as low as 25 below on Tuesday, and it would continue to remain bitterly cold through Friday.

Hanson with MDU assured that Sunday's main break was not normal.

"What happened today is a pretty rare occurrence,"he said, adding that lines are routinely checked and subject to routine maintenance.

They had yet to determine what caused the leak; Hanson said an entire section of the 8-inch, main-line pipe was replaced.

He advised residents to check www.montana-dakota.com on a regular basis; MDUplans to routinely update the site as to what areas workers are in and where they will be going.

Go online at www.bismarcktribune.com for a video and continued information on the natural gas outage.

Residents can also contact MDUat 638-3278, the Red Cross at 223-6700 or Morton County Emergency Management at 667-3307.

(Reach reporter Crystal R. Reid at 250-8261 or at crystal.reid@;bismarcktribune.com.)