Upsilon Sigma Phi fraternity house. (Photo West Philly Local)

Police are searching for two armed men who forced their way into and robbed a fraternity house at 42nd and Pine near 42nd and Baltimore Wednesday morning at around 2 a.m.

The fraternity members in the house, the University of Sciences students, were hosting a birthday party at the time, NBC10 reports. Students at Upsilon Sigma Phi fraternity house answered a knock on the door. The gunmen ordered the students to the ground, took cash – much of the fraternity’s newly collected dues from a safe in the house – and fled, according to police. One of the students was also attacked during the invasion as he told NBC10.

Penn and the University of Sciences planned to issue safety alerts to their students today.