Human Rights Watch (HRW) reported Thursday that Russian armed forces perpetrated three separate cluster munitions bombings of a Ukraine city, Mykolaiv.

Mykolaiv has a population of about 500,000. It is located on the road to Odessa, which is around 62 miles away. According to HRW, there were three separate attacks on the densely populated city on March 7, 11, and 13.

The first of the attacks, on March 7, left three citizens wounded. HRW analyzed the situation and found that the Russian forced used Smerch and Uragan cluster munition. Both types of cluster munition are subject to an international treaty ban due to their widespread indiscriminate effect and long-lasting danger to civilians. HRW noted that the use of such tactic could be considered a war crime.

On March 11, multiple attacks hit the Inhulsky neighborhood and the Pivnichnyy neighborhood. These are in the suburbs directly north of Solyani and .3 miles from a military base. Although there were reports of destruction of multiple locations, the most notable were a 10-story apartment building, many civilian vehicles, a nine-story building, and a preschool yard.

The attack on March 13 killed nine civilians who were waiting in line on the street at a cash machine. On that day, Russian forces attacked at least three areas of Mykolayiv with rocket artillery carrying submunition payloads. The bombing also damaged homes, businesses, and civilian vehicles.

Belkis Wille, senior crisis and conflict researcher at HRW, said: “Multiple residential areas in Mykolaiv were rocked by cluster munition attacks in the span of a week. Russian forces should stop using cluster munitions and end these clearly indiscriminate attacks.”

Other organizations have also reported Russia’s use of cluster munitions, including Amnesty International.