The incident happened about 11.30am on Monday at USP Beaumont, a federal prison in Beaumont, Texas.
The altercation involved members of the violent MS-13 street gang, two people familiar with the matter told The Associated Press. The people could not discuss an ongoing investigation and spoke to the AP on condition of anonymity.
The attack is just the latest example of serious violence within the beleaguered federal Bureau of Prisons. The agency has struggled through a multitude of crises in recent years, including widespread staffing shortages, serious employee misconduct, a series of escapes and deaths.
The lockdown, being instituted at the agency's more than 120 federal prisons across the US, was prompted by fears of potential retaliation and concern violence could spread to other facilities.
During a nationwide lockdown, inmates are kept in their mobiles most of the day and visiting is cancelled. Because of a spike in coronavirus cases in federal prisons, social visits at nearly every facility have been cancelled already.
The use of a nationwide lockdown is relatively rare. The agency implemented the measure in April 2020 as COVID-19 cases began skyrocketing in prisons nationwide, again after the insurrection at the US Capitol on January 6, 2021, and shortly before the inauguration of President Joe Biden later that month.
On Monday, the Bureau of Prisons said officers at the Texas prison observed multiple inmates fighting and responded to secure the area. Two inmates, Andrew Pineda, 34, and Guillermo Riojas, 54, were pronounced dead at a local hospital after the attack.
Two other prisoners were injured and taken to nearby hospitals for treatment.
There have been a number of serious security issues within the federal prison system in the last few months, including several inmate deaths and stabbings.
The Texas prison houses 1372 male inmates.
