Staff members of an Internet service chain in Xi'an resigned Saturday over retaliatory assaults they had suffered for barring minors.

Local police said Sunday they have stepped in to investigate an assault that happened Friday night at the Sanfuwan Outlet of the Hongshulin Internet Cafe Chain, which staff said was among a series of attacks by young people at the cafe. One of the staff, surnamed Chen, said he stopped seven or eight teenagers about to enter on the morning of May 6 because some of them looked very young. Chen asked to see their identity cards to verify their age. The teenagers refused and threatened to beat anyone who "dared to check identity cards." They tried to force their way into the cafe but were stopped.

Amid recent campaigns to crack down on illegal Internet cafes and to ban people under 18 from entering, Internet cafes in China have been ordered to check identity cards of guests before they are allowed in. Otherwise Internet cafes themselves will face harsh punishment varying from a fine to closure.