BAGHDAD (AP) — A bomb exploded on a busy street filled with shoppers in northern Iraq, part of a series of attacks that killed at least 19 people Friday, officials said, the latest in a wave of violence roiling the country.

The explosion struck a commercial street in Mosul, killing 12 people and wounding 30, police said.

Hassan Mahmoud, the owner of an ice cream shop along the street, said he was thrown on the ground by the powerful explosion.

"I went outside my shop to see pieces of flesh scattered all around the place with wounded people screaming for help," Mahmoud said. "The scene was horrific."

Earlier Friday, a bomb exploded just after Friday prayers as Sunni worshippers left the Ali Bin Abi Talib mosque in Baghdad's western Shurta district.

A second bomb, planted further down the street, exploded seconds later as worshippers tried to flee from the first blast, officials said. Police said the two bombings killed five people and wounded 15.

In the western city of Fallujah, a former al-Qaida stronghold 65 kilometers (40 miles) from Baghdad, gunmen opened fire on a security checkpoint, killing two police officers and wounding two, police said.

Hospital officials confirmed the casualties in the latest attacks. All officials spoke on condition of anonymity because they were not authorized to speak to reporters.

Attacks on mosques, especially Sunni ones, have increased recently. While it's possible that Sunni insurgents seeking to stoke sectarian hatred could be to blame for them, Shiite militias also may be behind the assaults.

Friday's violence comes a day after a series of attacks across Iraq left 30 people dead, most of them soldiers who were killed when two suicide bombers drove their explosive-laden cars into a military base in the town of Tarmiyah, just north of Baghdad. Tarmiyah is also a former insurgent stronghold and home to Sunnis.

There was no immediate claim of responsibility for the attacks of the past two days.

But suicide attacks and large bombings, especially against Iraqi forces but also civilians and places such as markets, cafes and mosques are a favorite tactic of al-Qaida's local branch. The terror group has recently escalated its campaign of violence in order to thwart the Shiite-led government's efforts to maintain security.

Violence spiked in Iraq since a deadly security crackdown on a Sunni protest camp in April, with the pace of killing reaching levels unseen since 2008. Friday's attacks bring the death toll across the country this month to 96, according to an Associated Press count.