Police are investigating fraternity rivalry as the possible motive behind a grenade attack that injured a cashier and damaged four vehicles at an apartelle in Caloocan City early Friday.

The grenade was thrown at about 4:47 a.m. into the hallway near the cashier’s booth at Fhiolan Apartelle on M.H. Del Pilar Street corner 2nd Avenue, Barangay 120, police said on Saturday.

The explosion caused thick smoke and sent shrapnel into nearby parked vehicles.

The victim was identified as a cashier at the apartelle, who suffered a fragmentation wound to her left thumb. She was taken to Caloocan City Medical Center for treatment.

The four damaged vehicles were a Honda Civic, Toyota Fortuner, Toyota Vios and Ford Ranger.

Police identified the suspects as Romeo Cunanan, alias “Togo,” the motorcycle driver, and John Michael Manuel, alias “Bodoy Liit,” his passenger.

Another suspect, identified only as alias “Ali,” was also named in the investigation.

Witnesses reportedly identified the suspects as members of the Magic 5 or M5 Fraternity. All remain at large.

Police said the attack appeared linked to an ongoing rivalry between M5 and Tau Gamma Phi, whose member Aniceto Pagulayan owns the establishment.

Pagulayan told investigators that M5 members had previously caused disturbances in the area and were allegedly involved in an incident the previous month in which bottles were thrown at his firetruck parked along J. Theodoro Street.

Police are continuing their investigation and reviewing available CCTV footage to establish the circumstances surrounding the attack and locate the suspects.