Iran has executed three men accused of killing police officers during anti-government protests in January, state media say, the first hangings to be carried out in relation to the demonstrations.

Among the men was teenager Saleh Mohammadi, a member of Iran’s national wrestling team, sources have told CBS, the BBC’s US partner.

The executions took place on Thursday morning local time in the northern Qom province after the Supreme Court upheld their death sentences, Iran’s Tasnim news agency reported.

The nationwide protests, which began in December and escalated in January, were met with a violent crackdown by the Iranian authorities. Rights groups say thousands of people were killed.