A?man has been detained by police in Shanghai after a remote-controlled bomb exploded inside a locker at a supermarket in Jiading District.

The bomb went off at about 2pm yesterday, destroying several lockers used for customers' bags at the three-story RT-Mart supermarket on Xinyu Road. No one was injured, police said.

The suspect, surnamed Qu, was caught in Jiading three hours after the blast.

Man held after supermarket blast in Shanghai

"I was startled by a deep and heavy booming sound at 2pm," said 37-year-old Pan Huayi, boss of a tea store near the supermarket.

"It sounded like great thunder strikes as it was raining hard. I didn't realize that it was an explosion until people rushed out of the supermarket."

Pan said he saw police officers gathering at the supermarket at about 1:30pm. They blocked off the entrance.

Customers in the store were told to leave immediately with a message broadcast over loudspeakers about a "fire drill." People outside were not allowed to enter.

Pan said he saw two young women quarreling with a security guard who wouldn't let them in to shelter from the rain. Then he heard the explosion.

"We tried to sneak in due to the heavy rain," said one of the women, a local resident surnamed Fang. "Then there was a big bang from the entrance where we were standing."

Fang said that when the bomb exploded there were still some customers inside, but she didn't see any injured people.

The Jiading government said a staff worker at the supermarket had received a call at 1:10pm from a man threatening to blow up the store.

Staff immediately started searching every corner of the supermarket and called police after finding a suspicious device inside a locker on the ground floor.

However, a bomb disposal team and firefighters failed to arrive before the device went off, causing damage over an area of 9 square meters.

After the blast, about 100 people - policemen, bomb disposal experts, urban management officials and supermarket security guards - teamed up to seal off the area around the building.

Everyone working in the building and nearby small stores were evacuated while police used dogs in a search for other devices.

Passersby who gathered around the sealed-off area were told the supermarket was holding a fire drill.

At 9:30pm yesterday, police were still on duty outside the building.

Residents living nearby said the supermarket, the largest in the Fengzhuang area, was very popular, but few people put their bags in the lockers unless they were forced to do so by security guards.