WASHINGTON — The federal prison system was placed on a nationwide lockdown on Monday after a gang fight at a high-security penitentiary in Beaumont, Texas, left two inmates dead, the Bureau of Prisons said in a statement.

While deadly fights break out with some regularity in federal penitentiaries, the bureau rarely locks down all 120 of its facilities in response.

“In an abundance of caution, the Bureau of Prisons (B.O.P.) is securing our facilities as a temporary measure to ensure the good order of our institutions,” Kristie Breshears, a bureau spokeswoman, said in a statement. “We anticipate this security measure will be short-lived.”

Ms. Breshears said the bureau would monitor events within its facilities and adjust its operations as the situation evolved, but declined to elaborate further for safety and security reasons.

The lockdown was reported earlier by The Associated Press.

Several inmates at the Beaumont prison started a violent altercation around 11:30 Monday morning, and four people were taken to a hospital for treatment, according to the Bureau of Prisons.

Two of those inmates — Guillermo Riojas, 54, sentenced to 38 years in prison for carjacking and interfering with interstate commerce, and Andrew Pineda, 34, sentenced to six and a half years on racketeering charges — were pronounced dead by hospital staff members, the bureau said.

No staff members or other inmates were injured in the altercation at Beaumont, a high-security prison that houses 1,372 male inmates. The Federal Bureau of Investigation was called in to investigate.

Officials worried that the deadly fight, which included members of the violent Salvadoran street gang MS-13, would set off violence at other facilities, according to a person briefed on the bureau’s decision, who spoke on the condition of anonymity to discuss a continuing investigation.

Officials began to lock down all federal prison facilities on Monday afternoon, meaning that inmates were generally confined to their cells.

While the bureau’s unusually severe response indicates that the fight was unique in its potential to create ripple effects, the violence was also in keeping with troubles that have long plagued the Bureau of Prisons.

This year alone, the bureau has announced four inmate deaths and three escapes, as it continues to struggle with staff shortages, health issues stemming from Covid-19, violence, mismanagement and employee misconduct.

This month, Michael Carvajal, who was appointed to run the Bureau of Prisons in February 2020, said he planned to resign. Mr. Carvajal agreed to stay on until a successor was in place.

The A.P. reported in November that more than 100 employees at the bureau had been arrested and convicted of or sentenced for crimes in the past three years, prompting Senator Richard J. Durbin, Democrat of Illinois and the chairman of the Judiciary Committee, to call for Mr. Carvajal’s resignation.