Masked Shi'ite gunmen stopped cars in western Baghdad, grabbing Sunni Arabs off the street and killing at least 37 people, police said, in a dramatic escalation of sectarian violence in the country. The attack in the dangerous Jihad neighborhood was apparently in retaliation for the car bombing of a local Shi'ite mosque the night before that left two dead. Police Lt. Maitham Abdul-Razzaq said 37 bodies were taken to hospitals and police were searching for more victims reportedly left dumped in the streets. He also said US and Iraqi forces had sealed off the area. Deputy Prime Minister Salam Zikam Ali al-Zubaie, a Sunni, called the attack "a real and ugly massacre," and threw responsibility on Iraqi security forces that are widely believed to have been infiltrated by Shi'ite militias blamed for the surge in recent sectarian attacks. "There are officers who instead of being in charge should be questioned and referred to judicial authorities," al-Zubaie told Al-Jazeera TV. "Jihad is witnessing a catastrophic crime." An Interior ministry official, speaking on condition of anonymity for security reasons, said Shi'ite militiamen wearing masks and black uniforms were roaming the neighborhood and checking people's identity cards, presumably for Sunni names. "They are killing civilians according to their identity cards," he said.