HUMBLE, Texas -- A boy accidentally drove a vehicle into an Humble dental office Tuesday afternoon, killing his mother, officials told KPRC Local 2.

Officials said Lisa Lewis, 44, had just finished her dental appointment at Monarch Dental Associates, on Bender Road at FM 1960, shortly after 2 p.m. and asked her two sons, ages 12 and 17, to pull up their van so she would not get wet from the rain.

Lewis was outside talking with two office employees.

"They went out to get the van to bring it closer to get mom out of the rain. Instead of the 17-year-old driving the van, the 12-year-old was behind the wheel. When mom noticed it, she was waving her hands, like, 'What are you doing?' And speculation is that the boy panicked. Instead of hitting the brake, he hit the accelerator," said Johnnie Ray Scroggins, Humble spokesman.

The car struck and killed Lewis and injured the two employees, according to authorities.

"I couldn't believe what I saw. Next thing I knew was he backed out and hit something backing out. I heard a scream," witness Mark Rabinovitch said.

The two other victims were taken to Northeast Medical Center in Humble where they are listed in critical but stable condition. One has a broken leg. The other has a broken hip. They are expected to recover.

People could only speculate as to why the 12-year-old got behind the wheel.

"Little brother probably saying, 'I can do it. It's not that far. Let me do it. Let me do it.' And older brother said, 'Hey, go right ahead.' And it was unfortunate and a definite accident," Scroggins said.

Lewis has eight children. Her husband is in Israel on a mission trip.

"They're a very nice family, a very close family, and it's going to be real hard for them," neighbor Terrye Enderle said. "They were over for Christmas dinner three years ago and just real nice and polite. The kids were well-behaved."

Humble police are investigating. The district attorney's office will decide if charges should be filed.