Kenyan authorities disputed claims by local officials that at least 20 policemen were killed in an attack by suspected al-Shabaab militants in the northeast of the country, saying that only five people were injured in the raid.

Kenyan Police Inspector-General Joseph Boinnet said officers on patrol in Garissa county came under attack late Monday. Other officers came to the scene and engaged in a "heavy firefight” that left two of them critically wounded and three with "minor injuries,” Boinnet said in an e-mailed statement.

At least 20 people died in the attack, in which the assailants used rocket-propelled grenades, Fafi sub-county Commissioner Geoffrey Taragon said earlier.

Mahat Osman, a local politician who visited the scene, said he saw as many as 20 bodies.

Taragon was unable to comment when contacted later because he was in a security meeting, while Osman wasn’t available.

The clashes in Garissa come less than two months after an al-Shabaab raid on a university in the county left at least 147 people dead. That was the deadliest attack on Kenya since al-Qaeda bombed the U.S. Embassy in 1998.

Somalia-based al-Shabaab has claimed responsibility for a series of attacks in Kenya over the past four years. The group says it’s retaliating over Kenya’s 2011 deployment of troops in Somalia, where the militants have been waging an insurgency against the government since 2006.

Al-Shabaab claimed responsibility for the latest raid, saying it ambushed a convoy in northeastern Kenya and killed police officers.

Kenya’s Interior Ministry said via Twitter that no police were confirmed dead.

"A combined security operation involving the National Police Service and the Kenya Defence Forces is managing the situation,” Boinnet said in the statement. An "operation to subdue the attackers is on course.