A man, believed to be in his 20s, was shot repeatedly around 9:50 p.m. on Sunday outside the Tedeschi store, 1886 Dorchester Avenue.

The Boston Police Department reports he was pronounced dead at the scene.

Around 2:45 a.m., Monday, a man and a woman, both in their 20s, were shot outside 92 Rosewood St. in Mattapan. both were taken to local hospitals, where they were pronounced dead.

In a statement tonight, Mayor Martin Walsh said the shootings are likely related - as is a murder last week on Callender Street.

"The last four shootings are likely related, and are a combination of gang violence and retaliation," Walsh said. "It is the understanding of the Boston Police Department that there were prior relationships between the victims and the suspects.

"In the coming days, I will be convening several groups to discuss actions we can take in several of the areas that I discussed with Commissioner Evans and his command staff," Walsh said. "We will work with all levels of government, law enforcement, and the community to reduce the trauma in our neighborhoods, get guns off the street, and address the underlying causes of violence."