WAJIR, Kenya, Feb. 16 (Xinhua) -- Suspected Al-Shabaab militants killed three Kenyan teachers and injured one other in an attack Friday on a school in the country's northeastern county of Wajir, officials said.

The militants in early morning attacked the Qarsa primary school near the borders with Somalia and Ethiopia, in a town about 70 km from Wajir town, the capital of the county, killing three non-local teachers, said Mohamud Saleh, coordinator of Kenya's northeastern region.

Authorities have been working to find another teacher who was allegedly shot in the hand and escaped with injuries.

Saleh said that ongoing efforts have been made to trace the killers, who escaped soon after the incident.

"This is (a) very unfortunate incident and the first of its kind in Wajir County," he said, noting that the militants had planted improvised explosive devices (IED) along the route to the school.

Police said the militants seemed to have planted enough IED on roads leading to the school, making it extremely hard for ambulances and reinforcement teams to get to the site on time.

"One of our vehicles that was responding to the attack was partly hit by an IED ... but all our officers are in good condition," said Mohamed Sheikh, Wajir Administration Police commandant.

Local residents said tension and uncertainty remains high in the entire county.

Northeastern Kenya has suffered grenade and gun attacks in recent years since Kenya took its troops to Somalia to fight the Al-Shabaab militia group in October 2011.

Several attacks believed to have been carried out by Al-Shabaab have occurred in Mandera, Wajir, and Garissa and Dadaab districts of northeastern Kenya even as the military reports gains against the Islamist group by capturing their military bases and killing scores of them. Enditem