A crew member aboard the Coast Guard boat that hit a commercial catamaran in Charleston Harbor in December was texting just before the accident, according to federal safety investigators.

Although the cause of the accident still is under investigation, the National Transportation Safety Board said Wednesday that the find raises concerns about the potential for distraction.

"The use of wireless communication devices while operating vehicles in any mode of transportation poses an unacceptable distraction," said NTSB Chairman Deborah Hersman.

A Coast Guard spokesman said such regulations already are in place.

The accident happened around 8:30 p.m. Dec. 5, just after the annual Christmas Parade of Boats, a busy time on the Harbor. A 25-foot Coast Guard boat hit the tour boat Thriller, injuring six of the 22 people aboard.

They were treated at local hospitals; the boat suffered above-the-water-line damage. No one on the Coast Guard boat was hurt, and the vessel was not damaged.

The NTSB on Wednesday issued a recommendation that the Coast Guard address the use of cellular telephones and other wireless devices aboard U.S. Coast Guard vessels, in the wake of the Charleston collision and another in California two weeks later.

On Dec. 20, a Coast Guard shore-based response vessel carrying a crew of five collided with a 24-foot recreational boat with 13 people aboard. An 8-year-old boy was killed in the incident, and four passengers were injured.

Four petty officers are facing Coast Guard charges ranging from involuntary manslaughter to negligent homicide and dereliction of duty. A Coast Guard district commander will decide whether they face a court- martial, and the family of the dead child has sued the federal government for unspecified damages.

The NTSB said someone on the Coast Guard boat crew had been texting just before that incident as well.

"Accidents caused by distractions from wireless devices must cease," Hersman said. "Lives are unnecessarily put at risk and lost."

The Coast Guard issued a policy July 16 that prohibits use of the devices by the boat operator -- the person at the wheel and throttles -- at all times while under way, said Lt. Cmdr. Chris O'Neil, chief of media relations at Coast Guard headquarters in Washington, D.C.

The policy prohibits other crew members from using the devices unless expressly approved by the boat operator, known as the coxswain, O'Neil said.

O'Neil defended the existing rule as very specific on the use of the electronic devices. That policy does not define the purposes or situations in which use can be authorized.

"It allows the coxswain to exercise judgment ... to determine whether it is prudent to allow use of that device," O'Neil said.

O'Neil declined to comment on details of the two accidents, citing ongoing investigations.