What’s known, and what remains unclear, about the deadly explosions in Iran

Here’s what’s known — and what remains unclear — about Wednesday’s deadly explosions in Iran:

• Authorities say the twin bombings killed at least 103 people and wounded 211 others.

• The attack is the deadliest to strike Iran since its 1979 Islamic Revolution.

• The second explosion occurred about 20 minutes after the first, which is often a technique used by militants to harm both civilians and emergency responders after an initial assault.