A surveillance video showing a man robbing a bank in Tianjin is sweeping Chinese cyberspace, causing heated discussion about his "unprofessional" behavior.

The video showed the man walking into the bank at 9 am on Feb 7. He then covered his head with a black mask and began hitting the counter window with a hammer. Two women clerks behind the window screamed, rang the alarm and fled.

The man kept hammering the glass calmly for almost four minutes.

Netizens said he hit the window at least 198 times until he ripped a hole in it and climbed through. By the time he had grabbed some money and was trying to get back out through the hole, two policemen had arrived.

The video aroused netizens' curiosity. They commented on the robber's calmness, the quality of the glass and the policemen's late arrival. Some even thought it was a robbery exercise staged by the bank. But others said the man was arrested and was later certified as suffering from mental illness.

No official information has been released.