The FBI is investigating whether a video claiming responsibility for a possible explosive device left at MacDill Air Force Base in Florida last week is credible, according to law enforcement sources.

The video, sent to the Tampa Bay Times via the app Signal, warns about more possible bombs. It also includes a timeline for a series of threats targeting the base last week, including the suspicious package discovered on March 16 and another threat that led to a lockdown at the base later in the week, according to the paper’s reporting. 

According to the newspaper, the person talking in the video is in silhouette and appears to be speaking in an altered voice. The person in the video claimed to be affiliated with a group that is against the war in Iran and U.S. deportation policy.

The person in the video also claimed another bomb was reportedly planted at the base on March 10, the newspaper reported. The person in the video said it did not detonate but claimed that any design flaws had been corrected.

The newspaper, citing public safety concerns, turned over the video to the FBI.

It is unclear whether the person or people behind the video are actually involved in last week’s incidents, but the bureau is examining the video and trying to learn who is behind it.

In response to a request for comment, the FBI said in a statement: “The FBI takes all threats seriously and is committing our vast and sophisticated resources to the investigation of last week’s threats at MacDill Air Force Base. We currently do not have credible information about any potential threats.”

The statement went on to say: “We continue to work closely with federal, state, and local law enforcement and private sector partners to keep our community safe. As always, we ask the public to please report anything that may seem suspicious to law enforcement immediately.”

The suspicious package was found outside the MacDill Air Force Base visitor center on March 16, officials said.

“Field screening was conducted on the contents of the package and identified possible energetic materials. Final lab analysis is not yet complete,” the FBI’s Tampa office later said in an X post.

The FBI has not commented about the possible improvised explosive device since that update.

The day after the discovery of the suspicious package, military officials raised the threat level of the base to FPCON Charlie — the second highest Force Protection level out of five levels indicating a serious threat has occurred.

Officials tightened security measures in place around the base and the following day issued a shelter in place citing an unspecified threat. The shelter in place order was lifted a few hours later.

MacDill Air Force Base is a critical command hub for the Pentagon, hosting U.S. Central Command — which directs military operations across the Middle East — as well as Special Operations Command.