D.C. police arrested an 18-year-old man Wednesday on charges that he intentionally drove a compact car into a transgender woman in the early-morning hours of July 5.

The 26-year-old victim remains in "critical but stable" condition a week after sustaining multiple injuries when she was run down about 3:20 a.m., said Acting Capt. Anthony Haythe of the homicide branch.

"We believe the vehicle was used as a weapon. Our victims received some very serious injuries," Haythe said at a news conference Wednesday night.

Detectives arrested Startwaune Anderson Wednesday after police obtained an arrest warrant Monday. Authorities charged him with aggravated assault while armed.

Her friends remain worried about her condition and her long-term recovery. The victim has endured a rough week and can communicate only by blinking her eyes, said Adriana Carter, a close friend of 12 years.

"She's breathing better. It has been a very tough six days," Carter said in an interview.

The accident happened in an area frequented by young people in the transgender community, activists said, but authorities don't know whether the incident was bias-related. Investigators say words were exchanged before the vehicular assault, but it was not immediately clear whether the driver or the victim had been arguing or knew each other.

"We cannot definitively say at this point that it was a hate crime. But we have not ruled that out and we are still investigating," Haythe said.

Officials declined to release many details of the investigation until Anderson has his first court appearance.

"This crime should be a bias-related crime. Let's not kid ourselves," said Ruby Corado, founder of Casa Ruby, an LGBT organization that has helped the victim over the past several years. Corado said the victim has volunteered for the group and has been close to the community, especially the outreach manager.

"We're targets. Every summer we face violence right here in our own homes," Corado said. "What we do know is someone is getting justice today, and that is the most important thing for us, given we still have to walk and live in this city."

Police said they recovered the striking vehicle, which they described as a compact car with damage to the windshield. Investigators used surveillance video and witness statements to help obtain an arrest warrant, but still seek the public's help, Haythe said.