ADDIS ABABA, June 30 (Xinhua) -- Security forces in Ethiopia have arrested around 300 people suspected of being involved a failed coup attempt on June 22, an Ethiopian official said on Sunday.

Abere Adamu, Chief Police Commissioner in Ethiopia's northern Amhara regional state, said around 300 people have been arrested suspected of being involved in the failed coup attempt earlier this month, state media outlet Amhara Mass Media Agency (AMMA) reported on Sunday.

Adamu, noting the formation of an investigation team, said the team has started a thorough investigation to apprehend any remaining suspects in the failed coup attempt. The officer added that normalcy has returned to the Amhara region, and urged the population not to heed rumors being propagated by destructive elements.

A failed coup attempt on June 22, suspected to be carried out by forces loyal to Asaminew Tsige, head of security at Amhara regional state, caused the deaths of dozens of people including the Amhara regional state president, Ambachew Mekonnen and Chief of Staff of the Ethiopian Army, Seare Mekonnen.

Migbaru Kebede, Attorney General of the Amhara regional state, Ezez Wassie, who was an advisor to the Amhara region's president, as well as Major-General Geza'e Abera, a retired former senior official in the Ethiopian army were also killed in the failed coup attempt.

On Friday, Billene Seyoum, Spokeswoman for Prime Minister Abiy Ahmed, said Tsige, the suspected mastermind of the failed coup, was shot dead Monday in a shootout with security forces.

The failed coup attempt also triggered a total internet blackout throughout the East African country as the Ethiopian government launched nationwide crackdown on the organized coup attempt, mainly in the Amhara region and the capital Addis Ababa.