Police said the shooting at the country's premier Indian Institute of Science in the southern city of Bangalore may have been a terrorist attack.
"This is a targeted attack. There was indiscriminate firing. Five people were injured," said Kishore Chandra, additional commissioner of police in Bangalore.
Institute registrar Uday Balakrishnan said one of the injured - a professor - later died.
The city immediately went on alert with police refusing to rule out a possible terrorist attack. Police found a live grenade at the site which was cordoned off.
"It might be a means to create panic," said Narayan Gowda, joint commissioner of police.
Police believe an automatic weapon was used and said although only one person opened fire on conference delegates; the attacker may have had accomplices.
Chandra said an international conference had just ended. And the shooting took place as people were leaving for dinner. Most of the injured were scientists and laboratory technicians.
The intruder escaped under cover of darkness.