Web measurement agency Hitwise found US news websites took a 3.83 per cent share of all online visits last week - up 11 per cent on the week before.
"As is typical with major news events, visits to broadcast media sites surged more sharply than visits to print category websites," wrote Hitwise's LeAnn Prescott.
"The market share of US visits to the broadcast media category increased by 28 per cent for the week ending 21 April, 2007, versus the previous week, while visits to print category websites were up only 11 per cent."
The worst such incident in US history, the massacre of 32 people plus gunman Cho Seung-ui himself, saw many students report observations on blogs and social network pages.
Journalists solicited many bloggers' eyewitness accounts, while one student who submitted camera phone footage from the scene to CNN's i-Report citizen journalism programme signed an exclusive distribution deal with the news network and NBC News provoked a mixed reaction when it aired a "multimedia manifesto" sent on DVD by Seung-Hui.
The episode marked "a great leap forward in the evolution of internet news", Times Online editor Anne Spackman told The Observer.
Lifting the lid on Hitwise data, Ms Prescott said MSNBC, NBC's online joint venture with Microsoft, saw a 102 per cent traffic spike while CNN.com surged by 75 per cent. A whole fifth of visits to CNN.com on the day of the incident went to CNN.com's video segment, she said.
Separately, citing official internal traffic figures, Beet.tv reported CNN.com video streams on Monday surged from an average 2.1 million to 11.4 million, beating the previous 7.7 million record set by videos depicting the execution of Saddam Hussein in December.
CNN,com's i-Report programme received some 100 submissions from the Virginia Tech campus but put into heavy rotation the video from Jamal Albarghouti, for which it paid an undisclosed amount.
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