Spokeswoman Billene Seyoum told journalists a "hit squad" led by Amhara's security chief Asaminew Tsige burst into a meeting on Saturday afternoon and shot regional president Ambachew Mekonnen and another top official.

The men were "gravely injured in the attack and later died of their wounds," she said.

"Several hours later in what seems like a co-ordinated attack, the chief of the staff of the national security forces Seare Mekonnen was killed in his home by his bodyguard."

Also shot dead was a retired general who had been visiting him, Billene added.

The bodyguard has been apprehended while Asaminew is still on the loose, sources said.

Analysts said the incident showed the seriousness of the political crisis in Ethiopia, where efforts by Abiy to loosen the iron-fisted grip of his predecessors and push through reforms has unleashed a wave of unrest.

"These tragic incidents unfortunately demonstrate the depth of Ethiopia's political crisis," said International Crisis Group analyst William Davison.

"It is now critical that actors across the country do not worsen the instability by reacting violently or trying to exploit this unfolding situation for their own political ends," the expert said.