Nairobi, Kenya (CNN) -- Two more police officers died after a grenade attack in Kenya's port city of Mombasa, authorities said Wednesday.
In all, Tuesday's attack has left three police officers dead and at least 11 wounded, police said
The attack came on the second day of protests after a radical Muslim cleric was killed in the same city Monday by assailants his wife claims were police.
Officers were on their way to help beef up security because of the ongoing riots, said police chief Aggrey Adoli.
The riots were spurred by Monday's killing of radical Islamic cleric Aboud Rogo Mohammed. Rogo was accused of supporting Al-Shabaab militants in Somalia and was blacklisted by the United States and the United Nations Security Council.
He also faced charges before a Kenyan court for planning terror attacks in Mombasa, Kenya's second-largest city and a popular tourist destination.
Police have said Rogo's death was under investigation.
One humanitarian group is calling for an independent investigation into the controversial cleric's death.
"The killing of Aboud Rogo is a serious crime that needs speedy independent and impartial investigation," said Leslie Lefkow, deputy Africa director at Human Rights Watch. "In the meantime, police should continue to stick within the law in confronting the riots sparked by Rogo's death."
Journalist Bihoff Mukoto contributed to this report.