The cause of the accident, some 25 miles (40 km) southeast of Houston, was not yet known. The names of those killed have not been released.
The helicopter crash did not affect navigation in the Houston Ship Channel, which links the busiest U.S. petrochemical port to the Gulf of Mexico, the Houston Pilots Association said.
Apache helicopter on military training mission in deadly crash, officials say
LA PORTE, Texas -- Texas Army National Guard officials say two crew members aboard an Apache helicopter on a routine training mission have died when their aircraft crashed in Galveston Bay just off the shoreline about 25 miles southeast of Houston.
Chief Warrant Officer Glen Webb says names of the victims are being withheld until their relatives are notified.
One of the crew members was from the Houston area, and the other was from out of town, CBS Houston affiliate KHOU-TV reports.
The helicopter was based at nearby Ellington Field.
Witnesses said the aircraft broke apart in the air late Wednesday afternoon.
Debris and a small oil slick were on the bay. A piece of the chopper’s blade was found on land near the crash site.
Divers were working into the night to retrieve the victims. The wheels of the helicopter poked above the water’s surface about 25 yards from shore near a vacant cruise ship terminal.
2 soldiers dead in Texas helicopter crash
Two soldiers died when their helicopter crashed into Galveston Bay on Wednesday, according to Texas Army National Guard Chief Warrant Officer Glen Webb.
The two service members had been participating in what Webb described as "a routine training flight." The AH-64 Apache helicopter crashed into the water near the Bayport Cruise Terminal in the city of Pasadena, around 3:50 p.m. (4:50 p.m. ET), Webb said.
Both soldiers were from the Texas Army National Guard's 1st of the 149th Attack Helicopter Battalion. Their names cannot be released until their families are notified through proper military protocol, Webb said at a news conference Wednesday evening.
Their bodies have been located, and search and recovery operations are underway, he said.
The helicopter had lifted off from Ellington Field Joint Reserve Base in Houston, said US Coast Guard Houston spokesman Petty Officer Andy Kendrick.
The incident is under investigation.
"All of our pilots are highly trained, highly qualified veterans who have been flying this aircraft for many years," Texas Air National Guard Master Sgt. Sean Cowher said at the news conference.