CAMDEN, N.J. (CBS) –– Investigators are working to determine the cause of a fire that broke out in an abandoned building in Camden Thursday evening, the fourth in three weeks.

According to police, the fire started just before 8 p.m. in a vacant former commercial structure on Park Boulevard and Empire Avenue.

READ MORE: Steam Leak At Vicinity Energy Plant In Grays Ferry Causing Loud Noise, Company Says

Crews were able to place the blaze under control in a little more than 30 minutes.

No injuries were reported.

READ MORE: WATCH LIVE: New Jersey Gov. Phil Murphy, State Health Officials Give COVID Update

On June 13th, a third, multi-alarm fire broke out at the vacant Concord Chemical Company along Federal Street near 17th Street. (see related story)

There are unconfirmed reports that there was suspicious activity in that area around the time the fire started. The ATF, the Camden County Prosecutor’s office and the Camden County Fire Marshall are all investigating.

MORE NEWS: Amtrak Forced To Reduce Service Along Northeast Corridor Due To COVID-Related Staffing Shortage