Boston University students evacuated Warren Towers twice within one hour last night because of a fire alarm malfunction in the lobby, a Boston Fire Department official said.

Captain Bradley Annis said both evacuations were caused by a malfunctioning alarm on the fourth floor lobby of the largest residence on campus housing nearly 1,800 residents.

“I hope this is the last time,” he said.

The first evacuation took place at around 6:15 p.m., and the second followed at around 7:20 p.m., according to evacuated students.

College of Communication junior Julia Harpin, who was in the dining hall when the second alarm went off, said students remained calm.

“A lot of people just stayed and kept eating,” she said.

Harpin said she thought most people stayed in the dining hall because they thought the second alarm was a prank, and “just someone getting their ‘yuks’ out.” Later, a dining hall manager instructed students to evacuate.

College of Arts and Sciences junior Shirley Field, who was eating with Harpin when the second alarm went off, said resident assistants directed students down both sets of escalators as they exited the lobby, telling them where to wait once they were outside.

CAS freshman Rachel Golden said there was no announcement regarding the nature of the second evacuation. She also said she saw no sign or explanation posted by the Office of Residence Life or other university staff members between the first and second evacuations explaining the nature of the problem.

However, Golden said both of the evacuations were orderly.

“It’s just kind of a hassle,” she said.