As mostly stated above, the bomb went off so draw the weapon and wait out, for all they know there may have been a suicide bomber or anything like that waiting to kill more innocent people, we are trained to do this as we serve the people and protect the country plus I wouldn't think twice about blowing and attackers head offif you look at one of the pictures in the article, the cop has their gun drawn... what are they going to shoot? an explosion? dust? fire?
So you don't expect them to be panicked? Just dust their shoulders off and tweet about it then go for a pint? They could have been inches away from having their faces plastered across 300feet of pavement.I wouldn't pull a gun, its a sign of panic... not the example to set for the civilians