Fire at a metals recycler in St. Paul burned for four hours until dozens of firefighters got the upper hand, authorities said.

The blaze struck AMG Resources Corp. in the 1300 block of Red Rock Road on Friday, according to the Fire Department.

Firefighters arrived about 7:40 p.m. to the building, which had no occupants at the time, to find it belching heavy smoke.

Getting to the flames was delayed because locked gates kept fire rigs from entering the yard of the business, which is near the Mississippi River and Pig's Eye Lake.

The blaze was centered in an open area in the middle of the building, where "it appeared ... a large pile of trash or recyclable materials" were burning, a statement from the Fire Department read.

Windy conditions allowed the fire to burn for longer than otherwise would have occurred. It was until shortly before midnight before the last of 50 fire personnel could clear the scene.

The circumstances leading to the fire starting remain under investigation.