Baghdad, Iraq ? Gunmen killed two Sunni Arab members of the commission writing Iraq’s new constitution on Tuesday, witnesses and political associates said. They were among at least 18 Iraqis killed Tuesday across the country.

Flanked by Iraqi vice presidents Adel Abed Mahdi, left, and Ghazi al-Yawar, right, Iraqi President Jalal Talabani speaks during a press conference Tuesday in Baghdad, Iraq. Talabani predicted Tuesday that Iraq's new constitution could be completed by the end of the month if a deal can be worked out with critics who have reservations about parts of the document. Two Sunni members of the panel drafting the constitution were killed Tuesday.

The commission members, Mijbil Sheikh Esa and Dhamin Hussein Ubaidi, were killed less than a month after they and 13 other Sunnis had been brought into the constitution-writing process in a bid to draw support away from the country’s insurgency.

The gunmen approached the car in which Esa and Ubaidi were riding from the front and behind on a street in the Karrada district of Baghdad, a witness said. A man traveling with the commission members also was killed and another was wounded.

Drafting a constitution is the primary task facing the Iraqi legislature that was elected in January. The process was delayed for months as political factions sought ways to include more Sunni Arabs, who had largely boycotted the January vote, leaving them with little representation in the 275-member National Assembly or on the constitutional committee.

The Shiite Muslim-led government of Prime Minister Ibrahim al-Jafaari and various political factions had hoped that by including more Sunnis in politics, they could siphon support away from the largely Sunni-driven insurgency that has ravaged Iraq for two years. But insurgents have targeted many Sunnis who have accepted positions in the government.

“We received threats a month ago,” said Saleh Mutlaq, a spokesman for the National Dialogue Council, a Sunni political group to which that Esa and Ubaidi belonged. “Now they’ve decided to assassinate all the committee’s Sunni members, so that no Sunni participates” in the constitutional process, he said. The committee is scheduled to complete a draft constitution by Aug. 15, but it may be finished by the end of this month. A referendum on the document is set for Oct. 15, and legislative elections are planned for December.

The attack occurred while the constitutional commission was meeting in Baghdad’s heavily fortified Green Zone. The commission’s head, Humam Hamoudi, adjourned the session when he received the news, the Associated Press reported. Hamoudi, a Shiite cleric, condemned “this criminal act that targeted the Sunni Arab brothers. Terrorism is against everyone and not against a specific sect.”