The three-day operation last week was announced in a bid to rid the streets of illegal weapons in a city where the number of homicides has surpassed 300 for the fourth year in a row.

Officers collected 1,860 weapons, a police spokesman told AFP. The city's mayor tweeted that a rocket launcher was among the haul.

Authorities offered $25 for large magazines, $100 for handguns and rifles, $200 for semi-automatic rifles and $500 for automatic rifles, promised anonymity to those who took part in the amnesty.

Home to 600,000 people, Baltimore allocated $250,000 for the operation, according to the city council -- as the Baltimore Sun's editorial board said the program was "likely to be a large waste of time, money and resources."

The daily newspaper said such buy-back schemes "do little to reduce the number of shootings or to get guns out of the hands of criminals intent on settling a score, defending their drug territory or protecting themselves from rival gangs and retaliatory shootings."

But police chief Gary Guttle told the Sun that if guns are "not in existence, they're not in the home, they can't be used, they can't be stolen."

"They won't contribute to our violence," he said.

The right to bear arms is guaranteed by the 2nd Amendment to the US Constitution, and there are weapons in one third of American homes.

According to health authorities, nearly 40,000 people died in the United States as a result of firearms in 2017, a figure that includes suicides.