A single-vehicle crash in Austin, Minn., killed four family members, authorities said.

The wreck occurred about 6 p.m. Thursday and left the car in flames on 2nd Drive SW., jus south of the Cedar River, police said.

Police and fire personnel arrived and "were unable to observe any signs of life from within the vehicle," Police Chief David McKichan said in a statement.

The chief said police believe the car had been traveling east on 11th Avenue SW., left the road, struck some trees, went down an embankment and came to rest on 2nd Drive near the water treatment plant. He said investigators are working to determine what led to the crash.

"We remain open to a number of possible factors, McKichan said. Inside the car were a man, a woman and two children younger than 5 years old.

"There is no way we can even attempt to get anyone out," one emergency responder said, while watching the vehicle burn, according to emergency dispatch audio.

"Investigators believe this to be a family unit," McKichan said. Identities will be released after family notifications and official confirmation from the Southern Regional Medical Examiner's Office, he said.

"This is an incredibly tragic event," the chief said, "and our department extends its condolences to the affected families and friends of the deceased."