The Boston Police Department was busy Monday investigating at least two shootings, two incidents of gunfire without injury and a carjacking.

At least one person was injured when two groups exchanged gunfire around 10 p.m. on Columbia Road near Geneva Avenue. One group was in a white mini-van, the other group was on foot.

Not long after, somebody walked into Carney Hospital with a gunshot wound sustained at the Fairlawn apartment complex in Mattapan (where a woman was strangled in November).

Around 2:45 p.m. residents along Greenfield Street reported hearing four shots. Police recovered at least one shell casing at Greenfield and Ridlon streets and were looking for two men in a small gray or tan car, possibly with New Jersey plates, both of whom got out and fired, before getting back in and fleeing toward River Street.

Around 9:45 p.m., police responded to Richmere Street and Cummins Highway for another report of gunfire without injury. This time, suspects fled in an Impala.

About the same time, a man was carjacked at gunpoint outside 1065 Blue Hill Ave. Police were looking for his Infiniti G35, with Massachusetts registration 145 PT5.