DES MOINES, Iowa (AP) - Authorities searching for two missing cousins said Wednesday that they have hunted for clues in a landfill and were summoning heavy equipment to more closely examine a northeast Iowa lake where the girls' bicycles were found last week.

As the search for Elizabeth Collins, 8, and Lyric Cook-Morrissey, 10, entered its sixth day, family members pleaded for officials to do even more. A congressman requested assistance from additional FBI agents to resume an all-out manhunt for the girls, last seen Friday leaving Elizabeth's house less than a mile from the lake.

"We're at a standstill," said Tammy Brousseau, aunt to both girls, told The Associated Press. "Bring in everybody. Bring in the army. Let's do this manhunt again. ... They disappeared into thin air."

Brousseau said she feared the girls were abducted, possibly by a sexual predator. She dismissed the possibility the girls might have drowned because they are good swimmers and their shoes weren't found.