An arson team was investigating a suspicious fire that damaged a post office in Riverside early Friday morning.

Firefighters were called around 1:51 a.m. to the 3600 block of Sunnyside Drive where they found a U.S. post office burning in a strip mall, the Riverside Fire Department confirmed.

Several fires were also found in nearby trash dumpsters, according to the Fire Department.

The fire inside the post office was contained to half of the building but caused some damage.

Several prepaid envelopes and cardboard boxes were burned, but no mail appeared to be damaged in the incident, according to the fire department.

An arson investigator was requested to determine the cause of the fires.

There were no injuries reported in the incident.