At least two Americans, one of them a young aid worker related to a retired senior U.S. naval officer, are believed to be among those trapped in wreckage after Haiti's earthquake.

The executive director of Haitian Ministries for the Diocese of Norwich, Conn., Emily Smack, says she believes two of the organization's staff are trapped in their mission house. The house partially collapsed during the earthquake Tuesday.

Smack identified the staffers as the mission's acting director, Jillian Thorp, and a management consultant, Charles Dietsch, who has been working with the ministry.

Thorp is the daughter-in-law of retired Rear Adm. Frank Thorp, who retired in August as the Navy's chief information officer.

Contacted at his home Tuesday night, Frank Thorp said he had been told that his 24-year-old daughter-in-law had tried to call for help using her cell phone and that her leg was badly injured.

He said Jillian had been living in Haiti since August when she took the lead at the mission house, which works with orphans and children with HIV. Before moving there, Jillian had traveled to Haiti several times with her family to participate in humanitarian work, he said.

"She's a superstar," he said of Jillian's devotion to aid work.

Smack said the Roman Catholic diocese mission house was located in Petionville, in Haiti's Mouru Hercule area. She said most of the homes are built using concrete blocks, cardboard and tin.

Smack said she had been in contact with Thorp and Dietsch until about 8 p.m. on Tuesday, when the cell phone they had been using died.

Frank Thorp said he has been pleased with the U.S. response by the military and State Department, who are aware of the location of the mission house and "who continue to assure us they are doing everything they can."

Thorp said he had been in touch with his son, also named Frank who had moved there earlier this month to be with Jillian. Thorp Jr., a television news producer, was safe, his father said.