A performance of "Amadeus" at the Source Theatre was halted after the first act last night following a dispute between theater founder Bart Whiteman and a group of handicapped senior citizens from D.C. Village.

A dozen elderly people, five of them in wheelchairs, had arrived late for the performance. Cecil Johnson, a recreation specialist from D.C. Village who was supervising the group, said that after they were allowed in, Whiteman, who also plays one of the lead roles in the play, told them they would have to leave. "I said we had paid for our tickets and we were staying," Johnson said. The tickets were arranged through Tickets for the City, a group that provides free or low-cost tickets for special groups.

Johnson said he was later told by a theater representative that the group was making too much noise, and that he had heard someone backstage say, "They've got to go." Because of that he decided during intermission that the group would leave. "I feel we were insulted," he said. "These people are handicapped and they don't get much cultural exposure." He said the bus taking them from the home in far Southwest was late and that loading all the wheelchairs had taken more time than he expected.

"We regret that they took offense at our reaction to their late arrival," Whiteman said when he announced he was canceling the second act. "This is a very difficult play and very difficult for me personally . . . Frankly, I have to admit failure in terms of handling the situation. I take responsibility for that."

Andy White, one of the extras who let the group in, said that if Johnson had called to say the group was going to be late and that several wheelchair patients were coming, arrangements could have been made to get them into the small three-sided theater with less disruption to the actors. "It's a very difficult situation," he said.

There were about 50 people in the audience, most of them in a party organized by a board member to introduce them to the playhouse at 1835 14th St. NW. The group, a well-dressed crowd, sipped complimentary champagne during the intermission, unaware of the contretemps over the visitors from the city's public home for the aged. Several of them said later that they had not heard the D.C. Village residents making any noise and did not understand why the show had been canceled.

"I feel badly that we didn't handle it better," Whiteman said. "But sometimes art has to step aside for life."