The US Navy has confirmed that eight service members assigned to the USS Abraham Lincoln carrier strike group attempted suicide during its extended deployment, with no deaths attributed to suicide, according to a letter obtained by NBC News.

NBC News reports on Thursday that acting Navy Secretary Hung Cao disclosed the figure in the letter sent to Senator Kirsten Gillibrand, a member of the Senate Armed Services Committee, in response to questions about conditions and the mental health of personnel serving with the strike group.

“Since the beginning of Lincoln’s deployment, there have been a total of eight suicide attempts across the strike group,” Cao wrote.

The figure includes members of the Lincoln’s crew, carrier air wing, strike group and destroyer squadron staff, escorting destroyers and embarked aviation squadrons.

About 7,500 service members, mostly sailors, are part of the strike group.