“What has become of our nation when children can no longer walk to a birthday party without fear?” Biden asked in a statement. The US President has long advocated tightening gun laws. “Firearms are responsible for the majority of child deaths in America, and the numbers are rising rather than falling. This is outrageous and unacceptable,” Biden said.

The police in the small town of Dadeville initially gave no details about the course of the crime and possible backgrounds. The local broadcaster WRBL reported that the investigators suspected a dispute among party guests as the trigger for the act of violence. A spokesman for the authorities called on witnesses to come forward. He said at least 28 people were injured, most of them teenagers.

Alabama Gov. Kay Ivey said Sunday that she shared her grief with Dadeville residents. “Violent crime has no place in our state,” she said.

Her grandson was among the fatalities, Annette Allen told the Montgomery Advertiser newspaper. It was his sister Alexis, who was celebrating her 16th birthday at the party, when shots rang out. “He was a very humble kid. Never in trouble, always smiling,” Allen said of the boy, who was due to graduate from high school in just a few weeks. “Everyone is mourning,” she said of the town of around 3,000 residents.

Gun law is a highly controversial issue in the United States. In the country, which has a constitutional right to own guns, there are an estimated 393 million publicly owned firearms. That means 120 firearms for every 100 residents. Firearm attacks with fatalities occur again and again.

The Dadeville incident came on the 16th anniversary of the deadliest campus shooting in the country’s history, which killed 32 people in Virginia in 2007.

Also on Saturday evening, two people were shot dead in a busy park in Louisville, Kentucky. In the same city, just days earlier, a bank employee shot dead five people at his workplace.

According to the non-governmental organization Gun Violence Archive, there have been 163 gun attacks in the United States since the beginning of the year alone, killing at least four people.