At least four people were killed and 20 others were injured when a gunman opened fire late Saturday night at a teenage girl’s birthday party in Dadeville, Alabama.

Local authorities have not yet clarified whether any suspects have been arrested.

“This action cost the lives of four people, in a tragic way,” State Police spokesman Jeremy Buckett said at a news conference.

Police have released few details, but have promised to make an announcement within the next few hours. An investigation has already begun to clarify the circumstances of the tragedy and the motive for the action. Law enforcement believes there was an altercation, according to local television station WRBL.

The attack took place at a dance hall in the city centre, where a teenage girl was celebrating her 16th birthday, the Montgomery Advertiser reported. Her brother, a high school student, is among the dead, the children’s grandmother told the newspaper. This young man had no criminal record and “he always had a smile on his face”the woman added.

“No city should experience such tragedies”Dadeville Police Chief Jonathan Floyd commented.

Dadeville is a community of 3,000 residents northeast of Montgomery, the state capital.

The president of the USA Joe Biden was informed of the incident and is monitoring the situation, the White House announced.

Earlier Saturday, in another shooting incident, two people were killed and four were wounded at a park in Louisville, Kentucky. In the same city, last week, a young man opened fire inside the bank where he worked, killing five people.