At least 12 policemen were murdered, and more than 60 were injured in twin explosions inside a police compound in the Swat Valley in Pakistan's northwest on Monday evening, according to police and health officials.

The explosions, which occurred in rapid succession at approximately 8:20 p.m. local time (1520GMT), were said to have originated from ammunition storage within a Counter Terrorism Department compound.

At least eight injured are reportedly in critical condition, prompting authorities to anticipate a rise in the fatality toll.

Local broadcasters initially characterized the explosions as a suicide bombings, but police have not yet determined the nature of the explosions.

"According to preliminary investigations, it was neither a suicide bombing nor an attack," Counter Terrorism Department chief Shaukat Abbas told Anadolu via telephone.

He added that a detonation in the ammunition warehouse could have caused the explosions.

The deputy director of the department, Khalid Sohail, told Anadolu that the likelihood of a suicide bombing is remote because the explosions occurred deep within the compound, near the ammunition store.

Sohail stated, "There is no evidence that a suicide bomber breached the entrance security, entered the building, and detonated himself."

"It could be the result of a negligent explosion in the ammunition storage facility," he said, adding, "We are investigating the incident from every angle."

Sohail reported that the building containing the ammunition store was destroyed, while a second building sustained partial damage when several shells struck inside.

Former Nest of Militants

The picturesque valley of Swat, located in the northwest province of Khyber Pakhtunkhwa, was an epicenter of militancy until 2008 when a military operation pushed the militants into adjacent Afghanistan.

Geo News displayed rescuers attempting to extricate the deceased and injured from the rubble while others placed them on stretchers and loaded them into ambulances.

Another scene depicted a gantry removing massive chunks of the concrete debris in an effort to facilitate rescue efforts.

No immediate claim of culpability was made.

Earlier, Shehbaz Sharif denounced what he termed a "suicide attack."

Sharif tweeted, "The martyrdom of police officials deeply saddens the nation" and vowed to "eradicate the scourge of terrorism."