HOUSTON -- A north Harris County oil-field services equipment company asked the FBI to investigate after four contract workers were fired for hanging nooses at its factory, KPRC Local 2 reported Wednesday.

The unidentified workers -- three men and one woman -- have been accused of hanging nooses in two separate incidents at FMC Technologies' facility on Gears Road near T.C. Jester Boulevard.

About a month ago, a supervisor found a noose in a shipping area, officials said. The incident involved the female and two male workers. Another noose was found hanging at the same facility last week and involved the third man, spokeswoman MaryAnn Seaman said.

"The actions of the individuals involved in these incidents were reprehensible," company President Peter D. Kinnear said in a written statement. "At FMC Technologies we have zero tolerance for harassment or discrimination of any sort. We are all diminished when someone engages in immoral acts such as these."

A company spokeswoman said one of the workers confessed when he was interviewed about the incident, but he did not give a specific reason why it was done. The worker claimed, he meant no harm.

Community activist Quanell X spoke with company officials after several African-American employees contacted him.

"One of the African-American females who saw the noose was totally terrified. She didn't even want to come back to work. She was afraid to come to work," Quanell X said.

Quanell X asked company officials why they did not alert the FBI or any agency until after the second noose was found.

"When we learned of the second incident last week, the investigation was, of course, launched immediately, probably within a half-hour of when we heard this. And, upon those investigations, that contract worker confessed to having done that," Seaman said.

Some employees said they were afraid to go to work. Others said they believe the nooses were in retaliation to the Jena Six rally.

"We've taken it very seriously," Seaman said.

The company sent a memo to all of their employees worldwide that explained what steps they have taken and what they will do if racial harassment continues on their properties.

"I really was shocked to hear it," said Betty Spicer, who lives near the facility.

Some residents said they were uneasy and wonder what kind of people live among them.

"I'm not surprised at all," resident Trahman Samuels said. "Look at the majority of people that are racist -- they're trailer park trash. Most of them probably insecure with themselves. Let them do what they do."

Yolanda Smith, executive director of the Houston branch of the National Association for the Advancement of Colored People, called it a sad situation.

"It's taken us back to the days of the 1950s and 1960s," she said. "We have to be more cognizant of diversity. Education is the key."

According to Seaman, no complaints about the nooses have been filed with the Equal Employment Opportunity Commission.

Seaman said the company has notified law enforcement.

FMC Technologies employs about 12,000 workers and operates 33 facilities in 19 countries. Fortune magazine has named it the most admired oil and gas equipment service company twice.