Hundreds of angry mourners have advanced on the U.S. embassy in Baghdad to protest the deadly U.S. airstrikes this week.

Dozens of protesters entered the embassy compound, where they hurled water bottles at retreating security guards, the Associated Press reported.

Outside the compound, hundreds of protesters smashed security cameras and chanted "Down, down USA."

Photos from the scene showed a compound sentry box had been set on fire by protesters, and footage showed the crowd waving yellow militia flags and chanting, with several cars parked outside in the street.

The protests came after mourners held funerals for those killed in the airstrikes, then marched through the city's fortified Green Zone until they reached the embassy.

Representatives of Iraqi Hezbollah posted on Twitter that it was not the intention of the protesters to attack the embassy, but to hold a sit-in until the embassy is closed and the U.S. ambassador is expelled, the AP reported.

The attack on the embassy follows American airstrikes on an Iranian-backed militia operating in Iraq over the weekend. Strikes were conducted against five facilities in Iraq and Syria affiliated with Kata'ib Hizbollah (KH), which the Pentagon described as a group linked to Iran's Quds Force responsible for recent attacks in Iraq, including a rocket attack which killed a U.S. civilian contractor at the K1 Iraqi military base near Kirkuk Friday.

In the aftermath of those strikes, a top Iraqi militia chief warned of a strong response against the U.S.

A State Department official downplayed the threat of retaliation from Iran or Iran-backed proxies Monday.

This is a breaking news story. Please check back for updates.