Ottawa police are investigating after four shots were fired into a Lowertown building around 2 a.m. on Tuesday.

It comes after two men were arrested in relation to shots fired in the ByWard Market early Monday morning.

No injuries were reported in either case.

The Tuesday morning shooting was initially believed to be fireworks linked to Victoria Day celebrations but police said casings for a .22 calibre gun were later recovered near the building on York Street east of King Edward Avenue. There are no witnesses and no suspects, police said.

On Monday, police were called to the ByWard Market around 2:30 a.m. after reports of shots fired.

A short while later, police stopped a vehicle on George Street and recovered a loaded firearm. The two men inside the vehicle were arrested.

A 26-year-old man and a 20-year-old man are facing a total of 10 charges, including possessing a firearm without a licence or registration, possessing a firearm while being prohibited from doing so, and careless storage of a firearm.

Earlier this month, two shots were fired into the lobby of a Murray Street building, east of King Edward Avenue. No one was injured in that case.

Police have no indication that any of the shootings are related.

Anyone with information about any of the shootings is asked to call the Ottawa police guns and gangs unit at 613-236-1222 ext. 5050.