Russia has massacred hundreds of civilians in Kharkiv, northeast Ukraine, using indiscriminate shelling and banned cluster munitions, according to Amnesty International. The human-rights watchdog investigated 41 strikes in the city and found that civilians were killed while lined up for food aid, shopping, or simply just walking down the street. One apparent cluster-munition strike hit near a playground, the BBC reports. Cluster munitions have long been opposed by human-rights groups because they explode mid-air and haphazardly release a cluster of smaller bombs over a large area, meaning they can accidentally hit civilian areas. And if smaller bombs don’t explode on impact, they can pose a deadly threat in the ground for decades after they’ve been deployed. More than 120 countries have signed a treaty banning their use, though neither Ukraine or Russia are part of the ban. Russia has previously denied using cluster munitions in its war in Ukraine.