More than a thousand people showed up during the weekend to search for cousins Elizabeth Collins, 8, and Lyric Cook-Morrisseey, 10, who were last seen by their grandmother on Friday as they headed out to ride their bicycles, CNN reported.
"As we evaluate the accomplishments and results of the searches conducted this past weekend, we are not asking for any additional assistance from the general public," Evansdale Police Chief Kent Smock said in an e-mail early Monday, adding the volunteer effort is was being suspended for now.
Authorities said Sunday night there were no indications cousins the cousins were the victims of foul play though the possibility had not been ruled out, The Des Moines Register reported.
"We've covered everything we can cover with civilian people," said Marcus Norman, the Evansdale Fire Department's volunteer coordinator. "Law enforcement is still working on the residential areas and things of that sort."
A $15,000 reward is being offered in the disappearance of the girls. Their bikes were found about 4 p.m. Friday at nearby Meyers Lake. Elizabeth's purse and cellphone were found about 20 feet away.
Dragging the lake and an extensive search of the entire city and surrounding vicinity by the army of volunteers turned up no further sign of the girls, the newspaper said.
The girls' families said they haven't given up hope.
"Sometimes when you think about it, you wonder if they're dead somewhere, but you try to push those thoughts out of your mind," said Misty Cook-Morrissey, Lyric's mother. "It's been good talking to people. ... It keeps your mind off of what's happening."
Elizabeth Collins' mother, Heather Collins, said it would be unusual for her daughter to stray very far from home on her own.
"We've talked about that before," Collins said "We've told them they're too young to go far."