Ajman Police arrested a man on suspicion of stabbing an Asian woman to death, and causing injuries to three others.
The suspect is also believed to have set fire to the shop where the stabbings took place on Monday afternoon.
Lt Col Saeed Al Madhani, deputy director of the operations department at Ajman Police, said they received a report regarding a murder and a fire at a commercial store in the emirate's industrial area.
Police, ambulance and civil defence teams were sent to the scene.
Investigations suggested that the suspect, who police identified as MS, stabbed an Asian woman several times, leading to her death.
Police said he also stabbed three people working in the shop before setting it ablaze.
He was later arrested.
Firefighters put the blaze out.
Public prosecutors said the man has admitted to stabbing the woman, with whom they said he was having an affair.
They said he told them he had an argument with the woman before stabbing her.
The suspect is in custody and will be referred to court when prosecution investigations are completed.
