Several suffer serious injuries in 'mass casualty' boating incident at Lake Austin

A teenager is missing while one person was airlifted to a hospital and another was taken by ambulance with serious injuries after a boat ran aground at Lake Austin, in Texas, Sunday, authorities said.

The boaters were traveling downstream when they went over a wake from another boat, according to CE-BAR Fire Assistant Chief Ken Campbell. They lost control of their boat, bounced to the right, ejected at least one person, and then hit the bank on the river's right side, he said at the news conference.

In addition to the two people transported to a hospital with serious injuries, two others were described as having "potentially serious injuries." Also, a teen was listed as missing, according to Austin-Travis County Emergency Medical Services. Two people refused transport to local hospitals, the ATCEMS said.

Authorities declared the accident a Level-5 mass casualty incident.

The incident took place in a remote area and required the use of jet skis to move those who were injured. The responders are in "recovery mode," according to ATCEMS.

This is a developing story. Please check back for updates.

ABC News' Marilyn Heck contributed to this story.