Three MIT students involved in a Halloween prank that went awry were ordered Friday to pay $1,306 to the city of Cambridge.

A magistrate rejected a request from MIT police to formally charge the members of the Phi Kappa Sigma fraternity with disturbing the peace and illegally possessing fireworks.

On Oct. 26, the fraternity members planned to set off an explosive device inside a Lobby 10 lecture hall while promoting their Halloween party--a fundraiser for the Leukemia Society of America.

The prank backfired when the device exploded in a student's hand.

"He thought the device would add to the aura by going off in a puff of smoke," said Robert J. Sales, associate director of the MIT News Office.

The explosion sent one fraternity member to the hospital, and slightly injured two other students. The explosion brought bomb squads from Cambridge and Boston, and closed parts of the MIT campus for hours.

Middlesex County Assistant Clerk Magistrate Robert Pacheco on Friday ordered the students to pay restitution to the Cambridge Fire Department and to each perform eight hours of community service.

The court continued the students' case until next September, Sales said. At that point, their records are likely to be erased if they have remained trouble free, he said.

Although the Halloween fraternity party was canceled in the wake of the incident, members continued to raise money for the Leukemia Society of America.

Last Thursday, Phi Kappa Sigma members presented the society's Massachusetts chapter with a check for $14,267, Sales said.

"As a fraternity, they have traditionally recognized the importance of our mission," said Iris Gleason, executive director of the Massachusetts chapter in a press release. "We appreciate that."

--Wire dispatches were used in the compilation of this article.