Two police officers were shot dead in Kenya on Sunday in the northern town of Garissa close to the border with Somalia, police said, hours after a child was killed in a grenade attack on a church in Nairobi.Kenya has been hit by a series of grenade and gun attacks since it sent troops into Somalia last October in pursuit of Islamist al Shabaab militants whom it blamed for kidnapping its security personnel and Western tourists.The killing of the police officers and the attack on the church came days after Kenyan troops launched a surprise offensive on the southern Somali port of Kismayu, al Shabaab’s last stronghold, forcing the rebels to flee.Most of the inhabitants of Garissa, where the police officers were shot, are ethnic Somalis and the town is located only 180 km (111 miles) from Kenya’s border with Somalia.Herman Ndiema, Garissa’s deputy police chief, told Reuters the two officers were killed as they walked to a technical college they had been assigned to guard. Their killers drove up to them in a taxi, shot them dead, and then jumped out to steal their guns, he said.