Online news sites were stretched to the limit on Thursday, as people turned to the internet for information about the terrorist attacks in London.

Four bombs went off between 8:51am and 9:47am, crippling the city’s public transport system, killing at least 52 people and injuring hundreds.

The BBC experienced the most significant slowdown from 9am to 1pm GMT, according to Ken Godskind, a spokesman for web performance monitoring firm AlertSite.

“The availability of the BBC site was down to 81 percent [compared with the rest of the week], and its home page, which normally takes 1 second to load, was taking as long as 15 seconds on average during that four-hour period,” Godskind said.

CNN was also affected, but not as dramatically. “The availability of the site was 97 percent, and the time it took to load the home page increased from one second to 1.8 seconds,” Godskind said.

“We were monitoring, but it didn’t appear to have any performance issues. Maybe that’s because it’s not a site where people would go to find updates."

Keynote Systems, another internet monitor, tracked the UK sites of, the Financial Times and Sky News, said spokeswoman Della Lowe, and at one point, it took more than 40 seconds to download the home pages of the latter two organisations.

From 9:44am to 1:14am GMT, only about one in four readers could access the Financial Times site, Keynote said. From 10:44am to 11:44am, the BBC site was also available to only about one in four readers. As for Sky News, it fared even worse: at one point, it was accessible by only about one in six viewers.