SILVER SPRING, Md. (AP) - A gunman with what police described as "concerns" with the Discovery Channel networks took at least one person hostage in the company's suburban Washington headquarters Wednesday.

Montgomery County Police Capt. Paul Starks said police were communicating with the man. He would not say if the man works for Discovery Communications or worked there in the past.

A law enforcement official speaking on condition of anonymity because the investigation is ongoing said authorities have identified James J. Lee as the likely suspect. Police believe he has a handgun but have not confirmed that he has explosives, the official said.

Montgomery County fire spokesman Capt. Oscar Garcia said no one was hurt. He said bomb technicians responded to the scene and the initial report was of a suspicious package that might be explosive. He said some employees had left the building.

Montgomery County Police Cpl. Dan Friz told WJLA-TV that a tactical team was trying to get in touch with the gunman, who was being monitored on closed circuit TV.

Adam Dolan, a sales director in Discovery's education division, told The Associated Press by phone that he was heading to lunch with a co-worker when he heard there was a situation in the building.

He was told to go back up to the top floor, lock the door and turn off the lights. Eventually the workers were herded down a stairwell and told to go home.

"Everyone was very scared, but at the same time ... I think people were calm and collected and responded as one would expect in this situation," said Dolan, 28.

When he got to the bottom floor, he saw shattered glass near the company's daycare and suspected it was broken to get the children out. He later got an e-mail that all the children were safe and had been taken to a McDonalds.

Dolan said the company has unarmed security guards who won't let anyone into the building without a badge.

Another person inside the building told The Associated Press the gunman had something strapped to his chest and had hostages. The person asked not to be identified, saying people inside were told not to speak to the media.

ATF and FBI officials also said they were responding. Authorities descended on the area, and people were being kept away from the main drag of the downtown area where the building is located amid restaurants and shops. Traffic in the area was jammed.

Discovery Communications Inc. operates cable and satellite networks in the U.S., including The Discovery Channel, TLC and Animal Planet. Discovery shows include "Cash Cab" and "Man vs. Wild," and TLC airs "American Chopper" and "Kate Plus Eight."

Animal Planet also airs the controversial series "Whale Wars," about attempts by environmentalists to disrupt the Japanese whaling industry.