Some personal safety tips on a bad day:

As of 5 PM, there is no apparent danger outside of Boston. NYC and DC are both beefing up police patrols, but there are no reported threats.

The most dangerous thing outside of Boston is panic. Do not tell people to evacuate public areas, because a large crush of people heading to public transit can be dangerous. Whenever possible, friends and loved ones in major cities should stay where they are, and are almost certainly in no danger.

Cell phone service in Boston has been suspended. Use email to contact friends and loved ones. This report has been retracted, but networks are overloaded. Avoid calling cell phones if possible. Texts should work.

Wait a day or two before attempting to donate blood or other goods.

Do not respond to solicitations for money. Scam artists are already at work.

Do not immediately repost anything you read before confirming from other sources. Many initial news reports are wrong. Some media outlets may seem legitimate when they are not (such as the UK Daily Mail).

I have not yet seen any rumors of WMD, but they’re certainly going to happen. Disregard them unless you hear it directly from the police or a governmental agency.

5:25 PM: it is unclear whether there has been a third explosion at JFK Library in Boston. The latest report is that this did not happen. Take this as evidence that something is not true simply because it has been reported. Many media outlets are publishing first, confirming later.

5:27 PM: If you need to find someone in Boston, use the Google Person Finder at http://google.org/personfinder/2013-boston-explosions . The Boston Marathon is running a similar service for people who ran the marathon today. Updated with better URL.

5:29 PM: A guest on WBUR just got carried nationwide on NPR speculating on whether the IRS will be targeted on Tax Day. This is exactly the kind of thing I’m telling you to disregard. But if you are in Boston, by all means, do not try to file in person today.

5:31 PM: the URL for Red Cross Boston: http://www.redcross.org/ma/boston. Do not go there right now to find out how to contribute; if the server goes down, people in the area may not be able to reach it.

5:35 PM: Reports that the police scanner in Boston is picking up many reports of “suspicious packages”. These are bags left behind by people evacuating quickly. Some reporter may pick up this story and report it as “possibly many more devices”. Disregard. At this time, there were two explosions and two deactivated explosives, which have been reported as IEDs.

Also: IED means “improvised explosive device”. It does not mean that the devices were built by anyone related to Afghanistan, Iraq, or anywhere else that you might have heard of such things. It probably does mean that the people who planted these bombs have very few resources; the “improvised” part means that they’re made out of whatever materials were at hand.

5:43 PM: The American Red Cross Safe and Sound Registry. Check here if you can’t reach your loved ones; register here if you’re in Boston. The Mayor’s Office hotline to find people in Boston: 617-635-4500.

5:46 PM: NPR reports a suspect in custody being treated for injuries.

5:48 PM: NPR reports some cell phone calls are getting through. Regardless: use email, and leave the networks open for first responders and those affected. Cell phones in Boston cannot place calls or send texts.

5:58 PM: Ground stop at Logan for arriving aircraft has been lifted. No-fly zone over Boston still in effect. Both precautionary only.

6:02 PM: National Guard is assembling on Boston Common for disaster relief. PRI reports that the timing of the bomb was poor—had it gone off earlier in the day, would have been more casualties. This is more evidence that the criminals who planted the bomb were not well organized.

6:04 PM: many people on Twitter are posting a body count in Iraq of 31 dead. Some of them are foolishly tagging this with #BostonMarathon. I won’t be surprised if this gets rewritten and spreads a rumor about a higher death toll in Boston.

6:06 PM: @BostonGlobe Are you a Boston Marathoner who needs a play to stay? bit.ly/XD0xYq Have a place to offer runners? bit.ly/XD0CeB

6:11 PM: Earlier reports that cell phone service was shut down are apparently not true. Networks are overloaded but working.

6:31 PM: Hashtag #BostonHelp is shaping up to be useful for finding places to stay, sending folks out to help stranded runners.

Why you should not use the word terrorism today: “@DavidCornDC Doesn’t terrorism need a political or ideological motivation? Was Newtown terrorism?”

More to the point: Terrorism implies a far more organized event than what we’re seeing so far. It needlessly scares people. The most dangerous thing for most people is being caught up in a panic reaction. Do what you can to prevent this in your community.

6:35 PM: @BostonGlobe: MT @redcrosseastma: Due to generosity of our donors we don’t need blood at this time. Please schedule future donation redcrossblood.org