HATTIESBURG, Miss. (AP) — Four people were killed and scores of homes were flattened early Saturday when a tornado hitting in the dark of night ripped through a city in southern Mississippi, officials said.

The city of Hattiesburg said via its Twitter account that four people had died after the twister blew through the city and surrounding area. The twister was part of a wall of stormy weather traveling across the region, bringing with it rain and unstable conditions.

Mayor Johnny DuPree has signed an emergency declaration for the city, which reported “significant injuries” and structural damage.

The city also said via Twitter that Hattiesburg firefighters and police are going door-to-door to try to rescue victims.

Greg Flynn of the Mississippi Emergency Management Agency said rescuers are still searching the stricken area for more possible victims.

Flynn said “massive damage” was reported in a three-county area that was struck by a tornado at around 4 a.m.

Photos and television images showed the intensity of the damage. Cars were flipped over, sometimes piled on top of each other while parts of houses were ripped into shards of wood and debris.

Once tall trees were ripped from their roots and thrown across roads.

As dawn rose over the city, rescue workers and residents walked down streets strewn with debris and still wet from the storm.

The three counties affected are Forrest, Lamar and Perry counties. Flash flood warnings were also in effect for northern Forrest and Lamar counties, as well as southeastern Jones and Marion counties.

The National Weather Service said three to five inches of rain have already fallen, raising the risk of flooding. More rain — one to two inches — is possible.

The Mississippi Highway Patrol is reporting Interstate 59 north of Hattiesburg is closed due to debris. Downed power lines and debris have been reported over a wide area. The public is asked to avoid travelling.

Flynn said the tornado touched down in Lamar, plowed through Forrest and then struck Perry before dissipating.