BAGHDAD — A bomb exploded in the Iraqi parliament's cafeteria in a stunning assault in the heart of the heavily fortified, U.S.-protected Green Zone today, killing at least two lawmakers and wounding 10 other people.

The blast in the parliament building came hours after a suicide truck bomb blew up a major bridge in Baghdad, collapsing the steel structure and sending cars tumbling into the Tigris River, police and witnesses said. At least 10 people were killed.

The bomb in parliament went off in a cafeteria while several lawmakers were eating lunch, media reports said. In addition to the two dead, state television said at least 10 people were wounded.

After the blast, security guards sealed the building and no one — including lawmakers — was allowed to enter or leave.

A spokesman for the U.S. Embassy in Baghdad said no Americans were hurt in the blast.

The bombing came amid the two-month-old security crackdown in Baghdad, which has sought to restore stability in the capital so that the government of Iraq can take key political steps by June 30 or face a withdrawal of American support.

One of the dead lawmakers was Mohammed Awad, a member of the Sunni National Dialogue Front, said Saleh al-Mutlaq, the leader of the party, which holds 11 seats in Iraq's legislature. A female Sunni lawmaker from the same list was wounded, he said.

In addition to killing 10 people, today's bombing of the al-Sarafiya bridge wounded 26, hospital officials said, and police were trying to rescue as many as 20 people whose cars plummeted off the span.

The al-Sarafiya bridge connected two northern Baghdad neighborhoods — Waziriyah, a mostly Sunni enclave, and Utafiyah, a Shiite area.