Suspected Islamists have been blamed for the deaths of at least 23 people in separate attacks in north-eastern Nigeria.
Witnesses say gunmen apparently targeted hunters selling bush meat in Damboa on Monday, killing 18 people.
Another five people died on Tuesday when a group of men playing draughts was attacked in Kano.
The militant group Boko Haram, which is fighting to create an Islamic state, has staged many attacks in Nigeria.
Boko Haram has been blamed for the deaths of some 1,400 people in central and northern Nigeria since 2010. Last year alone, the group was linked to more than 600 deaths.
On Monday, gunmen opened fire at a market in Damboa in Borno state, targeting hunters selling meat from animals such as monkeys and pigs, local government official Abba Ahmed told journalists.
Strict Muslims are forbidden to eat this type of bush meat.
"Gunmen suspected to be members of Boko Haram came to the town market and shot dead 13 local hunters on the spot while five others died from their injuries at the hospital," the official said.
Damboa is located near the capital of Borno state, Maiduguri, the stronghold of Boko Haram. The militant group was founded in the city in 2002.
Meanwhile, reports have emerged of a deadly attack in Kano, the main city in northern Nigeria, 500km (310 miles) west of Damboa.
Gunmen riding on motorbikes opened fire on people playing an outdoor board game, police and witnesses say.
Gambling is also strictly forbidden under Islamic law.