A blast hits an office building in Xi'an, capital city of Northwest China's Shaanxi province, on Wednesday afternoon. [Photo/CFP]

XI'AN - No fatalities have been reported after an explosion wrecked a building Xi'an, capital of Northwest China's Shaanxi province, on Wednesday afternoon.

The blast,in an industrial park in Beilin District, occurred around 5 pm in the second floor office of a Chinese medicine company. Xinhua reporters on the scene saw flames, broken windows and glass littering the ground. Several cars parked nearby were damaged,

Pictures circulating on the Internet showed walls collapsed on the second of 10 storeys in west wing of the building, with heavy smoke billowing into the sky.

"The whole second floor is unrecognizable. It's on fire now," said a Sina Weibo microblogger who was thrown to the ground by the explosion.

Chen, another Weibo user, told Xinhua that she was working on the third floor of the building when the blast occurred.

"The blast happened before 5 o'clock. It was still working time, and there were many people in the building."

Some of her colleagues were injured by flying glass, and one struck by falling debris. The building caught a fire last year, Chen added.

The scene has been cordoned off and roads around the site blocked off to make way for the rescue operation, said Yang Tao, a local traffic police officer. Witnesses reported only a few minor injuries with the wounded being sent to nearby hospitals. At least 12 fire engines were in attendance.

As of 7 pm, the flames were out and firefighters had left the scene.

An investigation is underway.