The guard was shot in the shoulder by a man he came across while conducting a routine patrol of the factory. The guard, whose name was not released, is in stable condition after surgery at a local hospital, Freeport Police Chief Henrietta Gonzalez said.
The guard approached a man in a pickup truck parked in a suspicious area, she said. The man rolled down his window and told the guard he was taking pictures of the lights around Freeport's port area and the BASF plant, Gonzalez said.
When the guard reached to open his microphone to report to his dispatcher, the driver of the truck pulled a gun and fired, hitting him in the right shoulder, she said.
The shooter sped away, and the guard drove himself to the factory gate where he knew armed, off-duty Brazoria County Sheriff's officers, employed by the company, were posted. The 911 call was made at around 9 p.m. local time, she said.
The guard said the male shooter had dark hair, a dark mustache and had not recently shaved. He spoke in accented English, the guard told authorities.
The FBI is monitoring the situation but said the Freeport police is the lead agency, FBI agent Bob Dogium said. "Right now there's no indication that it was terrorism," he said.
Gonzalez said the suspect was driving a white, half-ton, dual-cab Chevrolet pickup truck with dark-tinted windows and no front license plate, which is required in Texas. The security guard said he could not see if there was a rear plate because the tailgate was down, she said.
Police have found the slug, which went through the guard's shoulder, and are testing it. Gonzalez said officers believe it came from a 9 mm or .380 handgun.
The Ludwigshafen, Germany-based BASF is one of the world's largest chemical manufacturers. The Freeport complex includes 16 plants, including an ammonia plant next to the deepwater cargo port. The facility produces adhesives, super absorbers, paints, nylons and plastics.
Freeport is on the Gulf of Mexico about 60 miles southeast of Houston.