Maj. Gen. Jeffrey Hammond, commander of U.S. forces in Baghdad, made sure to stand away from cameras at the end of a morning press briefing Saturday and showed two photos to a few reporters huddled around him. He said that out of respect to the families of the bombers, he would not show them publicly. “Judge for yourself,” he said when asked if the women were related, but he said they looked remarkably similar and “there are some indications they were mentally handicapped.”

The photos showed two women with narrow eyes (open) and broad noses, unusual features for Baghdad though not conclusive proof of mental disability. “The two women were used because they don’t understand what was happening and they were less likely to be searched,” Hammond said. Some reports stated that one of the women was known in the pet market she blew up as a cream seller with developmental disabilities. Women and teenagers have been used to carry bombs before.

Casualty figures still vary, with U.S. officials claiming a total of 27 people killed and Iraqi officials putting the number close to 100. But the effect was the clear, undermining the hope Iraqis had that the recent lull in violence can last. Though levels of violence in the city are down to around late 2004 levels–when the city was bloodied but hadn’t reached the anarchic mayhem of 2006–this was the worst bombing in months. And, it came after there had already been a gradual increase in large attacks through November and December. Iraqi and U.S. commanders are quick to paint it as a sign of desperation by terrorists trying to prove they are still operating and point to the shift to vest bombings because car bombings have been made more difficult to carry out. But newspapers here carried front-page headlines of the attack and some Iraqis wondered if bombings had returned as a daily terror. In casual conversations with NEWSWEEK staff, Iraqis said they were going to renew their wariness of crowds and some refugees delayed plans to return to Baghdad.

Commanders acknowledge that Al Qaeda may be adjusting to the increased American troop presence in Baghdad and the largely successful tactic of putting more soldiers in small neighborhood bases. It’s a pattern that has happened before, when insurgents have been beaten back by an offensive and then regrouped, figuring out the new routes for smuggling equipment and bombers. Hammond says the terrorists are making adjustments but his troops will stay “unpredictable” and keep the pressure on.

With reporting from Salih Mehdi