A special task force formed on Saturday to probe the gruesome killing of two Indian doctoral students at their Louisiana State University apartment has launched a massive manhunt for three suspects described as "black men".

A task force comprising the LSU police department, the Baton Rouge police department, Louisiana state police and the East Baton Rouge parish sheriff's office has been assembled to investigate the murders of Chandrasekhar Reddy Komma (31) and Kiran Kumar Allam (33), both from Andhra Pradesh.

The task force is attempting to identify and locate three young black males who were seen hurriedly leaving the vicinity of the apartment where the murders occurred on Friday night.

Though earlier it was suspected to be a lone case of home invasion, nothing appeared to have been stolen from the apartment, leaving police unclear about a motive, LSU chancellor Sean O'Keefe said.

The men got into a small to mid-size four door car, possibly occupied by a fourth person (driver), Baton Rouge police spokesman Don Kelly said.

The car was seen leaving the complex with its headlights turned out and headed south on Governor Claiborne before turning its lights back on and turning right (west) on Aster.

Police increased patrols as tension and fear gripped the student community in LSU, but the campus remained open today for the final exams.

"I feel so scared," said Misook Kim, an LSU student from Seoul, South Korea, who has lived in the same complex for three years.

"I've never felt safe here. I think I may try to move," Kim added. She said she did not know the victims.