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Four people were reported dead and a rescue operation was underway Saturday after a tornado wrecked buildings and left people trapped in their homes in southern Mississippi, Forrest County Coroner Butch Benedict and Hattiesburg city officials told NBC News on Saturday.

Damage caused by tornadoes in Hattiesburg, Mississippi, Jan. 21, 2017. WDAM

The Mississippi Emergency Management Agency said it had received reports of "extensive damage" in three counties — Forrest, Lamar and Perry — in the area of Hattiesburg, Miss.

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Four people were confirmed dead and Hattiesburg city officials said that the mayor, Johnny DuPree, had signed an emergency declaration amid "significant injuries and structural damages." It did not immediately give further information.

Forrest County Emergency Management said it could confirm only three deaths. The reason for the discrepancy was not immediately clear.

4 people confirmed dead from Tornado — City of Hattiesburg (@Hattiesburg_MS) January 21, 2017

Some people remain trapped in their houses, said Forrest County Emergency Management Director Glen Moore. He said it was too soon to estimate the number of injured people.

In addition, a fire department in Hattiesburg was damaged, Moore said.

"Search and rescue teams are being deployed to assist Forest County emergency management in the Hattiesburg area," the agency said in a statement.

Interstate 59 north of the city was closed, the agency said, and severe weather was continuing to move through the southeastern part of the state.

A tornado watch has been issued for parts of Alabama and Florida until 11 AM CST pic.twitter.com/ekWKug0DAP — NWS Tornado (@NWStornado) January 21, 2017

"There are power lines and debris over a large area so the public is asked to avoid travelling," the agency said.

William Carey University in downtown Hattiesburg also reported damage.

Damage caused by tornadoes in Hattiesburg, Mississippi, Jan. 21, 2017. WDAM

It came as a band of severe weather moved across the region, and the NWS issued a tornado watch for parts of Alabama and Florida until 10 a.m. ET.