UPDATE 6:45 a.m. Thursday
Anchorage District Attorney Clint Campion said Thursday he had been in contact with police during the incident.
"I consulted with APD last night and based on the information I received, I did not believe there was probable cause to support an arrest of the barricaded driver," Campion wrote.
Campion said he didn't have an update on the driver's status.
10:15 p.m. Wednesday update: Anchorage police reported they cleared the scene near the on-ramp from Dimond Boulevard onto Minnesota Drive. No one was taken into custody and the investigation is ongoing, police wrote in a release.
Earlier story:
Police are responding to a man who refuses to come out of his vehicle, parked on a highway on-ramp in South Anchorage, according to the Anchorage Police Department.
APD sent out an alert around 7:15 p.m., warning drivers to avoid the on-ramp, which connects Dimond Boulevard to southbound Minnesota Drive.
A large number of officers responded due to "an armed man barricaded inside of his vehicle," the release says.
The suspect is alone in his car, police said.
No injuries had been reported.