(Image source: MSNBC)

BY STEVEN SPARKMAN

You're watching multisource world video news analysis from Newsy. 

It’s being called Pakistan’s worst terrorist attack in months.
And the death toll continues to rise in the explosion that targeted civilians during worship.
MSNBC has more.

“A region where a key U.S. supply route goes through was rocked midday. During prayers in this country, a bomb went off at a mosque in the Khyber region. The attack killed at least 40 people, and is especially unsettling given Muslims are in the midst of the holy month of Ramadan.”

CNN reports -- even more shocking -- is the age of the bomber.

“Police now tell us that this was a suicide attack carried out by a teenage suicide bomber between 15 and 17 years old. Police say he walked into this mosque and blew himself up.”

The death toll is now at least 50, with another 100 injured.

The Khyber region is part of the tribal areas along the Pakistan / Afghanistan border. U.S. supplies and forces pass through the region, and any Pakistanis who are seen as sympathetic to the U.S. are targeted. (Video source: Express 24/7)

Though no group has claimed responsibility for the bombing, The Christian Science Monitor reports -- militants’ anger at perceived Muslim traitors is the most likely motive.

“Most of the victims belong to the Kookikhel tribe that is largely considered to [be] pro-government and anti-Taliban. The Pakistani Taliban has not claimed responsibility but officials have blamed the militants for the bombing.”

Another mosque in the same region was bombed back in 2009, killing 50 people. And the LA Times reports, there have been other deadly bombings, recently.

“Last fall, a suicide bomber attacked a mosque in the town of Darra Adam Khel, where residents had formed a militia to resist Islamist militants. At least 60 people were killed in that attack.”

Transcript by Newsy.