DAKAR, Senegal (AP)  Ugandan rebels in eastern Congo have ruthlessly killed at least 620 people in the past month, human rights groups said over the weekend.

The Uganda rebel group, the Lord’s Resistance Army, hacked to death villagers in its path as it fled a multinational military offensive aimed at driving it out of northeastern Congo. In December, it appeared that the rebels had killed nearly 200 people.

The significantly higher figure comes from a two-week mission to the region by the New York-based group Human Rights Watch and the Congolese rights group Justice Plus.

In a statement, Human Rights Watch said that many of the attacks appeared to have been premeditated and that victims’ skulls had been crushed with wooden bats and axes.