At the start of reporting the Boston bombing, there was an estimate of 3 dead, and 170 wounded. The death toll hasn't changed, but it seems like the number of wounded has increased as time has gone on.
As of April 22nd, one week after the attack: Third major paragraph
"...killed three people and injured more than 170..."
As of April 30th, more than 2 weeks after the attack): About a quarter way through the article
"...killed three people and left more than 260 wounded..."
What is the actual number of wounded victims in the Boston bombings?
Even assuming they didn't count everyone the day of the attack, they couldn't have miscounted by 90 victims a two weeks after the attack.