Dadaab District Officer Bernard Ole-Kipuri said the latest explosion occurred at 8:30 p.m. (1630 GMT).
Ole Kipuri said the injured three police officers who were with others were on a normal night patrol in the sprawling camp which has experienced insecurity incidents in the recent past.
“The officers who had just patrolled the expansive camp were returning to their police post but were attacked just 50 meters before reaching,” Ole Kipuri told Xinhua by telephone.
He added that after the hurling the grenade at the police officers, the attackers suspected to be insurgents from Somalia later proceeded to shoot other passersby indiscriminately although no civilian was injured.
Kipuri said that the three who sustained serious injuries have been admitted at the Dadaab district hospital. The administrator said no arrest had been made in connection to the incident but noted that the police were on hot pursuit of the suspects.
Dadaab town that hosts the four main refugee camps has witnessed a series of grenade, gun attacks and kidnappings which have been linked to members of the Somalis Al-Shabaab group. This is since Kenya took its troops to Somalia to pursue them.
Since the Kenya military incursion into Somalia several attacks believed to have been carried out by Al-Shabaab have occurred in Mandera, Wajir, and Garissa and Dadaab districts of northern Kenya even as the military reports gains against the military group by capturing their military bases and killing scores of them.