Woman in critical condition after being shot in the head at N Houston gas station

HOUSTON Texas (KTRK) -- A woman was shot at a gas station in north Houston, police say.

It happened in the 1300 block of Crosstimbers near the North Freeway around 9 p.m. Thursday.

The Houston Police Department said two groups of people in two separate cars got into some sort of altercation. That's when gunfire was exchanged.

A man drove the woman to the hospital, and she was later sent to the Texas Medical Center. She's in critical condition, according to police.

"We have a witness at the hospital that actually drove the female there, so we're trying to figure out what his involvement is at this point," HPD Lt. Larry Crowson said.

Detectives are working to find surveillance video. A description of the suspects was not immediately released.

The incident remains under investigation.