The mystery continues into what happened to two cousins who disappeared during a Friday afternoon bike ride.
Eight-year-old Elizabeth Collins and ten-year-old Lyric Cook were last seen around 12:30 p.m. Friday after they left their grandmother's house on a bike ride.
Their bikes were later found near Meyers Lake.
Monday night, family and friends came together for a prayer vigil at Heartland Vineyard Church in Cedar Falls after a 4th day of searching for the girls turned up nothing.
After a weekend outside, hundreds came inside to pray and find comfort that Collins and Cook will be found safe after 4 days of mystery and misery.
That includes parents and other family members of the girls.
"I know in times like this, it's good to be around family and they are part of our church family and we want to seek the Lord in this situation and bring comfort and peace with his holy spirit. That's what we want to see happen," said Reggie Hovenga, Associate Pastor of Heartland Vineyard Church.
Earlier Monday, as part of the search, police stopped cars on the street to see if anyone had seen the girls before they disappeared Friday.
Meantime, water from the lake drained into the Cedar River.
It's the latest effort by authorities to find the girls.
Their bikes were found by the lake Friday.
Authorities dragged every inch of it over the weekend but want to make sure they didn't miss anything.
"They were confident no one was in there but to be 100 percent sure we have to drain that lake to do that," said Richard Abben of the Black Hawk County Sheriff's Office.
Authorities say the lake is dropping at three inches an hour so it may take a couple of days.
They're going around the clock and are noticing that this case is getting increasingly more attention regionally and nationally.
Authorities say there's no need for volunteers Tuesday and they still are treating this as a missing persons case.
They say there's no evidence to suggest there's foul play.
They say family members have been very cooperative and that there's no-one they've wanted to talk with that they haven't been able to find.
Anyone with any information is asked to call the Evansdale Police.
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