Two policemen on patrol were attacked and seriously injured by a group of young men after midnight on Friday, at Nalasopara.
The constables, who were riding a bike, spotted the three men at Oswal Nagari and stopped to question them. One of the men attacked the cops with a hammer.
One of the policemen, Sandesh Ghegadmal, 26, was hit on the head and suffered serious wounds. As the other cop, Sashi Patil, 27, stepped up to defend his colleague he too was hit and injured.
They managed to catch the assailant, who was identified as Sharadchandra Sharma. But the two others ran away.
The two policemen are being treated at Alliance hospital in Nalasopara. Ghegadmal had to undergo stitches and he is under observation in the intensive care unit, said Irfan Nadaf, investigating officer at Nalasopara police station.
Not much is known immediately about the assailant or his accomplices. The police said they have registered a case of attempt to murder under sections 307, 353, 332, 333 and 34 of the Indian Penal Code that also carry punishment for assault to deter a public servant from discharging his duty.