Eleven people including the suspected gunman and his mother were killed in a shooting spree and car chase in southern Alabama on Tuesday, authorities and local media said.

The shooter, who was in his mid-30s, killed five people including the wife of a local deputy sheriff and her three-month-old baby at a mobile home in Samson, according to Wynnton Melton, mayor of nearby Geneva, Alabama.

His other victims included his own mother, two people killed at a convenience store and a man in a pickup truck who died during a car chase as the gunman apparently fired at random, said Mr Melton.

In all 10 people plus the gunman died, according to the website of the Dothan Eagle newspaper.

The shooting began in Samson, a small town in the southeastern part of the state and ended after a car chase and gun battle in Geneva, the county seat about 20 kilometres away, according to the FBI and local police.

"Officer Ricky Morgan rammed his car to distract him and was rewarded with a hail of bullets," said Melton. "One bullet grazed the shoulder of police chief Frankie Lindsey."

A police officer in Geneva said the gunman "shot at several vehicles on the highway and then he shot at Wal-Mart and Piggly Wiggly," a grocery store.

A statement from the Alabama Department of Public Safety said state and local law enforcement agencies had responded to "a series of at least four shooting incidents" involving what was believed to be a lone gunman.

The suspect "left at least nine victims dead before he died from a self-inflicted gunshot," the statement said.

Police said they expected to find more victims. There was no indication of a motive for the spree in which a house was also burned in a nearby county.