A Vancouver, Washington, woman is missing after falling into the Willamette River after her float tube snagged on a root ball on the Willamette River near Buena Vista Park south of Independence, Oregon, on Saturday. Search operations were continuing Sunday.

The Polk County, Oregon, Sheriff’s Office said Tracy Allen, 37, was floating the river with friends Saturday afternoon when their series of interconnected float tubes ran into a large root ball snag just off the west shore of Wells Island.

Two women floating with Allen were able to get to shallow water and make it to the island, but Allen was not seen again after going into the water. Two men with the party were able to avoid the snag, according to the Sheriff’s Office.

An extensive search of the area by multiple agencies using boats, a drone, side-scan radar and ground search teams were unable to locate Allen. The search was also aided by a REACH Air Medical Services helicopter but was called off at nightfall, the Sheriff’s Office reported.

Allen, who knew how to swim, was wearing a life jacket at the time of her disappearance, the Sheriff’s Office reported, but it added that the current in the area was strong and that treacherous debris from trees littered the area.