Twitter carried some graphic images of victims after the explosions, including blood-soaked sidewalks and people in the streets with severe injuries. One person urged users to focus on how to help rather than posting photos of victims.
Determining what's useful information and what crosses lines of decency or taste may come down to individual judgment, however. "There aren't really clear etiquette standards for using social media," said Sterling.
"As long as the event happens in a public space, there's no way to stop over-the-top or inappropriate information from getting out there," Weide said.
For sure, Twitter, Facebook and other social media sites were a useful source of information for many tracking the events. Google set up a Person Finder, as it did after the Japan earthquake two years ago, to help people connect with friends and loved ones after the incident.
Not surprisingly, the hashtag #bostonmarathon spiked sharply almost immediately after the attacks, said Hashtags.org, and mentions of "Boston" soared on Facebook, reported analytics company Topsy.