Washington, Dec 23 (IANS): Three people were killed and seven others injured in four separate shootings in the US city of Baltimore, Maryland state, authorities said.

One incident took place on Sunday afternoon and involved two unidentified suspects -- one with a rifle and another with a handgun -- who opened fire at a group of people lining up outside the iVilla Hookah Lounge, reports Xinhua news agency.

Seven people, including three teenagers, were injured in this shooting incident with no casualty, the Baltimore Sun reported.

Also on Sunday, a 35-year-old woman was shot dead in a downtown grocery store.

The two other shooting incidents occurred on Saturday, in which a woman was killed in a hair salon and a 21-year-old man nearby.

Police had made no arrests as of Sunday evening and offered few details about each of the deadly shootings, the report said.

Richard Worley, chief of patrol at the Baltimore Police Department, said the police "have no idea" about what motivated the suspects to commit the crime outside the hookah lounge, calling the criminals "brazen".

"The level of violence late into the weekend is completely unacceptable," Baltimore Mayor Bernard Young tweeted on Sunday, adding that police officers will be "working non-stop to identify suspects and bring the shooters to justice".