Five people have been hurt following a "minor explosion" at Southgate tube station in London.
Paramedics treated five patients at the scene during the incident shortly after 7pm on Tuesday evening - with two of those then taken to hospital.
Police closed the north London station and had said officers were dealing with a suspicious package.
But Scotland Yard soon ruled out terror and later said that initial investigations showed the explosion's cause was a battery short circuit.
A Met Police spokesperson said: "The scene has been examined by specialist officers.
"It appears at this stage that the cause of the explosion was a battery short circuit.
"The Met Police and BTP are working together to establish the full facts."
One eyewitness had reported a "burning smell" near to the scene.
Haluk Ozkan said: "I was waiting for a bus and when we approached the bus we could smell a rubbery burning smell.
"I could see people scurrying around the station not running but moving quite quickly. My partner saw someone take a fire extinguisher."
A Metropolitan Police spokesperson had said: "Police were called at 1903hrs on Tuesday, 19 June, to reports of an explosion and people running at Southgate underground station.
"Met officers remain at the scene along with colleagues from British Transport Police, London Fire Brigade and London Ambulance Service."
London Ambulance Service said that several ambulances and paramedics had been dispatched to the scene.
An LAS spokesperson said: We were called today at 7.02pm to an incident at Station Parade, N14.
"We sent multiple resources to the scene, including a number of ambulance crews, our hazardous area response team, a medic in a fast response car, an advanced paramedic and an incident response officer.
"We have treated three patients at the scene for minor injuries and have taken two people to hospital."
British Transport Police advised people to avoid the scene.