Heavy rain sent flash floods coursing through a narrow slot canyon in southern Utah's Zion National Park, killing three people and leaving four others missing, officials said Tuesday.

Three bodies were found a day after the group of four men and three women set out Monday to hike down the canyon, park spokeswoman Holly Baker said. They went canyoneering before park officials closed slot canyons that evening due to flood warnings.

The deaths come after 12 people died when fast-moving floodwaters on Monday swept away two vehicles near the Utah-Arizona border, about 20 miles south of the park. One person remains missing from the small polygamous town of Hildale, Utah.

In Zion, rescuers were waiting for water levels to drop before entering the canyon to search for the missing hikers.

The group hailed from California and Nevada and were all in their 40s and 50s, Baker said. She didn't have further details on their identities.

The first body was found around 1:30 p.m. Tuesday and a second body was found an hour later. The third body was found later Tuesday afternoon, Baker said.

Baker did not know if the bodies found were male or female.

Park rangers advised the group when they picked up their permit Monday that weather conditions were poor, but until canyons are closed, Baker said rangers leave it up to visitors to determine whether it's safe to continue their excursions.

The park doesn't close canyons until actual flooding occurs, which was around 5 p.m. Monday, she said.

Someone who knew the group alerted park officials Monday that they hadn't checked in after their trip. Park rangers found the group's empty cars at the canyon's trailhead that evening.

The group was in Keyhole Canyon, which narrows to 6 feet across in parts and involves climbing, swimming and rappelling.

Baker said the park received 0.63 inch of rain in one hour Monday.

The National Weather Service issued flash flood warnings through 7:45 p.m. Tuesday for Zion National Park, as the saturated area could be hit again with light to moderate rainfall.

The warning said rivers and streams at the popular park and in neighboring Springdale and Rockville are already elevated and additional rain will swell the waterways to dangerous levels.

Zion is the most-visited of Utah's five national parks and attracts nearly 3 million visitors a year.