A 75-year-old man is hospitalized in grave condition after an assault following an altercation on a Metro Transit bus near the intersection of Chicago Avenue and Lake Street.

Minneapolis police were called at 2:39 p.m. Wednesday to the 2900 block of Chicago Avenue, where they came upon the victim and spoke with witnesses, who said the victim became involved in a verbal exchange on the bus. When the victim got off the bus, a suspect and three others followed him. After another altercation, the suspect, believed to be in his 20s, struck the older man, causing him to fall and strike his head.

Minneapolis police announced an arrest Thursday night in the case by members of the violent criminal apprehension team and SWAT personnel. The 23-year-old man was booked in the Hennepin County jail and was being held on suspicion of aggravated assault. The Star Tribune generally does not identify suspects before charges are filed.

Police spokesman John Elder said investigators, along with Metro Transit police, were reviewing all surveillance video connected to the incident, including from the bus and nearby businesses and homes to determine the suspect’s identity.

“This continues to be a very active investigation and we anticipate additional arrests,” Elder said in a statement.