MILWAUKEE (AP) -- Police walked shoulder-to-shoulder through wooded areas and dive teams searched the sewers Wednesday in an escalating search for two young boys who disappeared while playing together Sunday.

Officers have also been searching vacant houses, vacant vehicles and the homes of registered sex offenders in the area where the boys were last seen, but there has been no sign of them, said police spokeswoman Anne E. Schwartz.

With no trace of the boys and no evidence of any crime, divers were called in Wednesday to search the neighborhood's sewers and a nearby lagoon to rule out a possible drowning. Officers were also searching by helicopter and expanded their ground search to a nearby state park and surrounding streets.

Police officials said at a news conference Wednesday afternoon that there was no indication the boys' families had anything to do with their disappearance.

"If I had a chance, I'd say, 'Boys, please come home. We've got everybody worried about you guys,'" she told CNN. "Everybody out here just wants you home."

The two were last seen playing outside a home around 3:30 p.m. Sunday. One of their grandfathers told them to come inside, but they asked to keep playing, Schwartz said. The grandfather called police about 8:30 p.m. Sunday when the boys didn't return.

A Florida group called A Child Is Missing was also helping police in the search. The group called all home and business telephone numbers within a mile of where the boys were last seen and played a recorded message about the pair, Schwartz said. The National Center for Missing and Exploited Children posted pictures of the boys on its Web site, as did America's Most Wanted.

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