Tuesday’s rock concert by the Pixies at Portland’s State Theatre ended with a rousing finale – and enough smoke to set off alarms and summon the fire department.

Theatrical smoke or fog used throughout the show became especially thick during the band’s encore song, “Into the White,” and set off a smoke detector in a projection room at 10:53 p.m., according Capt. John Brennan of the Portland Fire Department.

The theaters’ doors were opened, the smoke cleared, and the alarm was reset, Brennan said. Firefighters determined that the theatrical smoke caused the alarm to go off, but were not sure what the exact source of the smoke or fog was, Brennan said. Dry ice, a solid form of carbon dioxide, is often used for such effects.

No one from the State Theatre or publicists for the Pixies returned calls or emails to provide details Wednesday.

Since the band was finishing its encore and the show was nearly over, some fans left without knowing alarms had gone off. Others heard the alarms and were directed to exits by theater staff. The show was sold out and the theater can hold more than 1,600 people.

“The alarms went off and they were high pitched, sort of like a guitar, so at first they were hard to make out. Then the band put down their instruments, and we realized those were alarms,” said Jeremy DaRos of Portland, who was at the show. “So people started filing out, but there was never a sense of panic in the crowd.”

The show had begun around 9:10 p.m. DaRos and other fans who knew the band’s usual set list knew that “Into the White” would likely be the last song. But because of the alarms, it ended more abruptly than usual, in some fan’s opinions, with band members putting their instruments down and walking off stage.

Two fire engines and a ladder truck responded to the alarm, but all had left the scene by 11:20 p.m., Brennan said.

Scott Dolan, of South Portland, a former Press Herald reporter, was sitting in the balcony when the alarms went off. He said people who were leaving were directed by theater staff to emergency exits, leading to a fire escape stairway.

Scott Girouard, of Saco, said he thought the show was over and started leaving before he knew alarms had gone off. But as he left he noticed theater staff asking people not to stop at merchandise tables and head out of the theater.

Girouard and other fans said they enjoyed the concert and the smoke alarms did not spoil the experience.