A man held two security guards at gunpoint last night--one of them for about an hour--in the American Broadcasting Company building at 1717 DeSales St. NW after he had chatted with them about his tastes in music and then demanded that he meet with the network's "top reporter."

He also told them that he was carrying a bomb, but police who arrested him after the incident began said the only weapon he carried was an unloaded .45-caliber automatic.

A spokesman for ABC World News Tonight in New York said the gunman "wanted to make some kind of statement." He never was able to make one, however, to anyone but the two guards, one of whom was forced to accompany him to an upper level of the building in his apparent search for a network newsman.

A D.C. police spokesman said late last night that the gunman's motives remained vague. "His specific reasons are not clear," said Lt. Hiram Brewton. "A lot of what he said didn't make sense. We're not clear what his message was."

Police said they arrested David John Mullin, 25, of Mount Pleasant, S.C., and charged him with kidnaping while armed in the incident.

At about 6:15 p.m., shortly before the network's evening news telecast began, a man entered the building's lobby and began talking with the two guards about how he liked rock 'n' roll music, according to Ed Fouhy, the ABC bureau chief in Washington. Roy Whitlow, one of the guards, said the man then suddenly demanded, "Give me your top reporter."

Whitlow said the man then produced the .45-caliber automatic pistol from an athletic bag and pointed it at security guard supervisor Greg T. Dority. Whitlow said the intruder and Dority then walked up a staircase, with the gunman jabbing the pistol in Dority's back.

According to Fouhy, Dority, 24, told the gunman that he was taking him to the news studio. Instead, the security guard took the man the building's vacant sixth floor. After pounding on doors to rooms he knew were locked, Dority tried to persuade the gunman that no one he wanted to see was in. He then took the man to the fifth floor, which also has no ABC offices, Fouhy said.

There, Dority was able to talk the man into laying down the pistol and giving himself up to waiting police, a police spokesman said.

Meanwhile, police arriving at the scene quickly evacuated about 50 people from the seven-story building while the 140 who remained were warned to stay in a secure place. A police Special Operations team armed with shotguns searched the building as a police helicopter circled overhead.

The 6:30 and 7 p.m. broadcasts of ABC World News Tonight went on as scheduled from basement studios in the building while the incident was under way.

No mention was made of it during the first broadcast, but at the close of the second and after the man's arrest, anchorman Peter Jennings took note of it, saying: "Finally, if we seemed a little tense this evening, it is because during much of the broadcast a man with a gun has been in the ABC News bureau here in Washington, though not in this studio. He took a security guard hostage. The police came and found him. He's been taken into custody, the security guard is safe, and even us reporters, we don't know much else."