Navghar police late evening arrested the men.
Police said that Surajbhan Soni, a resident of Malad was seen roaming in the Indira Nagar slums in Bhayander (east) at around 2.30am. He was noticed by four men, in their 20s, who were drinking in the nearby open ground.
The men kicked and punched him on the abdomen and fled from the spot. The youth was noticed by some passersby who informed the police. Cops reached the spot and rushed the victim to the hospital but he was declared dead before admission. He was later identified.
Based on closed circuit television images and informers police nabbed the four men on Saturday evening. The men told the police that Soni was roaming suspiciously in the area. When asked what he was doing there in the wee hours, he did not give a convincing reply.
The men said that they thrashed the victim and left him injured. They said that they had never seen the victim in the locality earlier and mistook him for a thief.
The accused have been booked under IPC section 302 for murder.