Pagers, used every day by health care professionals, became a deadly weapon Tuesday as thousands of them simultaneously exploded in Lebanon.

The Hezbollah militant group said it is conducting a "security and scientific investigation” into the explosion of pagers across Lebanon on Tuesday.

This week's explosions have also deepened concerns about the scope of potentially compromised devices, particularly after such bombings have killed or injured so many civilians. Here's what we know so far.

Thousands of pagers and radios held by Hezbollah members have exploded across Lebanon and Syria, killing more than a dozen people and wounding thousands. The attacks bear the hallmarks of Israel's Mossad intelligence agency,