A described racist employee of a key US defense contractor opened fire on fellow workers here on Tuesday, killing five and wounding eight before killing himself, police said.
It was the latest in a string of chillingly similar workplace massacres that has plagued the US in recent years.
Local radio station WMOX identified the gunman as Douglas Williams, saying he was described by co-workers as a "white racist."
Four of his five victims were black.
Bobby McCall, whose wife Lanette was one of the black victims, told reporters she had complained that Williams had "made threats against black people."
A police spokesman said the gunman arrived at the Lockheed Martin plant dressed in camouflage gear and armed with a revolver and semi-automatic rifle and opened fire at about 9:30am.
Lauderdale County Sheriff Billy Sollie told CNN television the killings appeared to have been random, adding that "several of the victims were found at their workstations."
John Smith, the town's mayor, said Meridian was traumatized by the attack.
"There's shock, there's horror and great, great grief," he told CNN. "It's not supposed to happen in a city like Meridian.
"Who knows what goes through the human mind, the human heart?"
Meridian, population about 30,000 people, is near the border with Alabama. Its economy is heavily dependent on military contracts.
Lockheed Martin, whose plant here is about 20 years old, said in a statement from its Marietta, Georgia, office that it was "shocked and saddened by this tragedy and express our deepest sympathies to the families" of the victims.
The company, headquartered in Bethesda, Maryland, next to Washington, is a key US defense contractor whose products include components of the F-16, F/A-22, F-35 JSF, F-117, T-50, C-5, C-130, C-130J, P-3, S-3 and U-2.
Company spokesman Jeff Rhodes in Marietta told AFP he could not explain how a heavily armed man could have entered the plant, which is supposed to meet Defense Department security criteria, without challenge.
"All of those things will be evaluated on what happened and what went wrong," Rhodes said by telephone. "It's all under investigation right now."
Tuesday's shooting was the last in a string of workplace massacres in the US in recent years.
The last was in Jefferson City, Missouri, last Wednesday, when an employee in an auto parts factory killed four co-workers, wounded five, then killed himself.