At least 17 people were hurt on Thursday when a man detonated a hand grenade at a crowded place in Yemen's northern province of Hajjah.
Security sources said the attack followed an argument between the attacker and other people in the area but gave no further details.
The wounded were taken to hospital for treatment, the sources said.
On the other side, eyewitnesses said they had found a shopkeeper dead in his grocery in Sana'a.
Stabs were found on the body of Khalid Alawi, 30, from Mahweet province who was killed in the Al-Sunaina district where he lived, they said.
Those behind the crime have not been identified yet.
An investigation into the incident is underway.