Unknown gunmen shot dead a Criminal Investigation Department (CID) officer in Kenya's northern town of Garissa near the border with Somalia, a government official told Xinhua on Friday.

Garissa County Commissioner Mohammed Maalim said the police officer was shot dead inside the mosque in the Hagadera area in the restive Garissa town.

"It's quite unfortunate that the gunmen shot dead the CID officer who was reading Koran inside the mosque in Garissa and during the sacred Eid-Al-Adha celebrations," Mohammed told Xinhua by telephone.

He said the officer was shot in the head from behind by someone who seemed to target him a few minutes past 1:00 p.m. local time.

"The CID officer was a young man who was recently posted in the region. It seems his assailants targeted him. I don't know what is wrong with the people," he added.

Eid-Al-Adha celebrations are held when Muslims traditionally pilgrim to Mecca and Medina.

Garissa and neighboring districts near the border with Somalia have been the site of increasing grenade and gun attacks targeting both Kenyan security forces and civilians since October 2011, when the Kenyan military entered southern Somalia in pursuit of the Al- Qaida linked Al-Shabaab.

The Kenyan government has publicly attributed the attacks to Al- Shabaab, which declared last year that it had joined the Al-Qaida network.

More than 80 people including 20 security officers have been killed in over 20 attacks in the northeastern region.