(NECN: Katelyn Tivnan) - These pictures we took Monday show Boston Marathon runners and onlookers being directed away from the scene of the Boylston Street explosion.
Thousands trying to stay calm in the face of danger with little information.
Dr. Amy Wachholtz of UMass Memorial Medical Center says many people who witnessed the events are just starting to process the experience.
"Even people further away from the epicenter still feel very closely tied to what went on with the bombings," Dr. Wachholtz said.
Wachholtz says everyone will process the experience differently, but says most will suffer some form of acute stress disorder.
"Prepared for fluctuating emotions, prepared for increased vigilance about your surroundings, that's very normal," Dr. Wachholtz said.
Wachholtz is encouraging those who were connected to the event to be aware of their emotions. She says it is important to talk about what happened with loved ones.
For those with personal connections to September 11 and other tragedies, it can also increase stress and trigger old memories.
"Very normal if you have difficulty sleeping start to have flash backs are more geared up but not in a positive way in irritability and easily angered," she says.
Wachholtz says not to cope with unhealthy behaviors including alcohol. She says while many people's sense of security has been impacted, it is important to reconnect to the events in a positive way.
"I think we'll all slowly have to put back the pieces of our memories and redevelop that sense of safety and community," Dr. Wachholtz said.
Boston has set up a hotline for finding friends and family: 617-635-4500; If you have info. regarding the perpetrators in the crime, call: 800-494-TIPS.