WASHINGTON (Reuters) – Major public events in the United States like the Boston marathon need greater security but officials must steer clear of moving toward a “police state,” Boston’s top cop said on Thursday at a congressional hearing into last month’s bombing.

The city’s police commissioner, Edward Davis, called for more use of surveillance cameras and other technology as well as special police units and more undercover officers as ways to provide tighter security. But the public’s privacy must also be protected, he added.