Archaeological exploration of the Alamo has unearthed the remains of three unidentified individuals, Texas officials say.

A teenager or young adult, an infant, and a large adult were discovered in the Monks Burial Room and center of the Alamo Church while crews were beginning the process of installing moisture monitoring equipment, according to a joint statement released by the Texas General Land Office (GLO) and the Alamo Mission Archaeological Advisory Committee. Crews were working in a part of the 300-year-old structure known as Long Barrack to determine what elements are impacting the building and to develop a restoration plan.

The Alamo was built as a mission on the banks of the San Antonio River in 1718 and housed church members and Native American converts for 70 years until the Spanish government claimed it in 1793, according to History. The structure was moved from its original site six years later after a devastating hurricane destroyed the grounds. Just a few hundred yards to the north, missionaries rebuilt a chapel, convent, small dwellings, storehouses, and workshops. When first established, founding father Fray Antonio de Olivares reported 50 different tribes in the area that were shortly decimated by epidemic disease and raiding activities, notes the National Park Service.

The Alamo is the sole remaining structure of the Battle of Alamo, a 13-day siege pivotal to the Texas Revolution. Between February 23 and March 6, 1836, a group of rebel colonists of the US and Mexican defense took up armed resistance to defend against the central Mexican government’s advancement northward. An army of 1,000 Mexican soldiers invaded, resulting in the death of around 200 Texan defenders, including American folk hero Davy Crockett.

It is unclear whether the discovered remains are of Native American descent. Officials note that long-established human remains protocol was activated and an onsite tribal monitor was immediately notified.

“The Committee was promptly notified following the discovery of the remains and has been fully briefed by Alamo Archeologist Kristi Nichols. It is important for all applicable laws to be followed and the Alamo project team is doing just that,” wrote the Alamo Mission Archaeological Advisory Committee in a statement, adding that in recent years, human remains were also discovered in the Alamo in 1989 and 1995.

Under the Native American Graves Protection and Repatriation Act (NAGPRA), federal agencies are required to consult work in collaboration with tribes to investigate and determine the next steps for human remains “whenever archaeological investigations encounter Native American cultural items.”

IFLScience reached out to the GLO but did not receive a response at the time of publication.