Montgomery County investigators were trying to determine Tuesday why a Buick LeSabre accelerated outside a Sam’s Club in Gaithersburg and nearly hit two small children, who were pushed to safety by their mother, before plowing into the store and striking two men in a food court area. One of the men lost part of a leg, officials said.

The driver of the sedan, Subinoy Mazumdar, 77, of North Potomac,was not injured. He spoke with investigators after the crash and was described as cooperative.

No one was killed in the chaos. But a man identified by police as Dimas M. Chavez, 76, of Potomac, who lost part of a leg,was taken by helicopter to the Maryland Shock Trauma Center in Baltimore, where he was listed in critical condition and was expected to undergo surgery Tuesday. The other man struck inside the store, Thaan Buithuan, 33, of Boyds, was taken to Suburban Hospital in Bethesda with non-life-threatening injuries.

One factor that may have averted more injuries: After the LeSabre crashed into the store, it hit a large pallet of merchandise — described by one official as stacks of sports drinks — that slowed the car down.

“We’re fortunate that more people didn’t get hurt,” said Capt. Tom Didone, commander of the traffic division at the Montgomery County Police Department.

911 audio

AUDIO: On Tuesday, a driver smashed his 2002 Buick LeSabre into a Sam's Club in Gaithersburg, injuring two men inside the store. Here is a recording of a 911 call from someone at the store.

SOURCE: Montgomery County Fire and Rescue Service.

No charges had been filed against Mazumdar. Officials didn’t know whether the crash was the result of driver error or a mechanical problem, said Capt. Jim Daly, the department’s spokesman. One witness told investigators there was the sound of an engine accelerating prior to the crash.

Just before 1 p.m., the Buick was traveling through the parking lot of the store, in the 600 block of North Frederick Avenue, just east of Interstate 270 and about 10 miles north of the Capital Beltway. A 31-year-old woman was walking outside of the store with two children, ages 1 and 3. Based on initial reports, the younger child was in a stroller or shopping cart, and the 3-year-old was walking. At some point, the mother saw the car coming at them and reacted immediately.

“The mom was able to push them out of the way,” Daly said.

The woman, identified as Sheila R. Orellana, 31, of Derwood, suffered minor injuries and was taken to a nearby hospital for a checkup, police said.

The Buick continued toward the store and struck a large metal service door to the right of the main entrance. The car also smashed through part of a wall to the right of the service door.

The car apparently hit Chavez near a support pillar, which may have contributed to him losing part of his leg, Daly said. Chavez had been near a cash register where shoppers pay for their food, he said.

Two members of the military who were in the store came to his aid. Two police officers quickly arrived, one from the Gaithersburg Police Department and the other from the county police, Daly said. A tourniquet was applied to Chavez’s leg, he said.

The store was closed after the crash and was set to be shut for the remainder of Tuesday, Daly said. He said that the store didn’t have structural damage but that officials determined it needed to have the service doors working to reopen because they served as an emergency exit.