June 23 (Bloomberg) -- Iranian police massing in force broke up a demonstration over the disputed presidential election just hours after the Revolutionary Guards said they would crush further protest.

Police used tear gas and fired shots into the air to quell yesterday’s rally in central Tehran, the Associated Press reported. Witnesses said helicopters hovered overhead as about 200 protesters gathered in Haft-e-Tir Square before they were dispersed, AP said.

Security forces were deployed in the capital to prevent further demonstrations after hundreds of thousands of Iranians took to the streets in more than a week of rallies. At least 17 people have been killed in the worst internal violence in the oil-producing nation of 66 million since the shah was overthrown in 1979.