Two workers were killed in a fuel tank explosion at an Ajman factory on Sunday, police said.
The force said three other people were injured following the blast at an industrial area in the emirate at about 11am.
They have been taken to hospital for treatment.
The severity of their injuries was not disclosed.
Emergency services - including police, fire crews and the ambulance service - were sent to the scene.
Police said the deceased workers were welding on top of one of the large tanks when sparks flew inside the fuel containment area, causing the explosion which claimed their lives.
Three workers from a neighbouring factory were injured after being hit by fragments of the tank, which were sent into the air by the force of the blast.
All of the casualties are from unspecified Asian nations, police said.
Maj Gen Sheikh Sultan bin Abdullah Al Nuaimi, Commander-in-Chief of Ajman Police, said the incident was caused by breaches of safety and security rules.
He said permits had not been granted by Ajman's Civil Defence to carry out such work with fuel on the premises.