Canadian police are revealing new details on an attack that occurred mostly on an Indigenous reserve last month, when they say one man killed 11 people with a knife, including his brother.

Myles Sanderson, 32, is alleged to have killed 11 people, including his brother Damien, and attacked a total of 29 people on Sept. 4.

Royal Canadian Mounted Police have since raised the death toll to 11 from 10 after now counting Damien, 31, who was initially involved in planning the stabbings in the Canadian province of Saskatchewan. Nine of those killings took place at the James Smith Cree Nation.

“In the aftermath of the Sept. 4 tragedy, our officers have been working tirelessly to investigate all aspects of the attacks,” a Thursdaystatement from the Royal Canadian Mounted Police Assistant Commissioner Rhonda Blackmorereads. “This includes the events and interactions leading up to the homicides until the arrest of Myles Sanderson.”

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The Saskatchewan RCMP reports that it received 4,600 calls from the public between Sept. 3 and Sept. 8, as information “based on what is currently known” points to Damien stealing a vehicle on Sept. 3 and entering an RV, before reportedly giving officers a fake name when they asked him who he was. The most recent photo police had of Damien was reportedly from 2014.

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He and his brother were then involved in “at least three violent altercations” with other people and had been selling drugs at the First Nation reserve in the days leading up to the stabbings, but authorities say they were not made aware of them before the attacks.

The Saskatchewan RCMP did not immediately respond to PEOPLE’s request for more information.

“Our investigators continue to corroborate witness statements with physical evidence and exhibits to create an accurate picture of the motives behind these crimes and why some of the victims were targeted,” Blackmore shared in the statement. “This will take time to complete and the reality is, we may never really know exactly why.”

According to theNew York Times, many community members believed that Damien was killed while trying to stop his brother, but both were initially charged with first-degree attempted murder and breaking and entering in the attack. The Crown has since dropped all charges following the deaths of the two men.

source: people.com