(CNN) Chicago police officers have seized more than 10,000 guns this year, Chicago Police Superintendent Eddie Johnson said.

That's about one gun every 47 minutes.

"There's nothing more dangerous for a police officer than confronting a suspect armed with a gun," Johnson said in a news conference Tuesday. "Tensions are high in these scenarios and the stakes are even higher."

Last week, a Chicago officer was shot in the head while pursuing a bank robber, Johnson said.

Chicago Police Superintendent Eddie Johnson

"Psychological damage from being involved in a shooting like this is another factor," Johnson said. "These wounds may be more difficult to see but they can be just as devastating."

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