[What a week. Here’s a quick-and-dirty essay typed up this morning.]

Friday morning America woke up to more mayhem — a manhunt for a terrorist in suburban Boston. The whole city on lockdown. One suspect dead. Officer slain. Another officer shot. Thousands of officers geared up and ready for battle.

It was, and is, utterly captivating. It also is almost unendurable. A person would be forgiven for turning off the television, shutting down the computer and going back to bed to hide under the covers. For those of a gentle disposition, this was all too much like an episode of “24” or a Bruce Willis movie.

This may have been the most chaotic and unnerving week in recent American history. An Elvis impersonator allegedly mailed poison letters to Washington (as many people have noted, Elvis would never do a thing like that). And in West, Tex., a fertilizer plant exploded as if hit with a small nuclear bomb, killing at least 12 people and leveling multiple city blocks.

It seems that the third week in April has become our time of calamity. The Branch Davidian fire (1993), Oklahoma City (1995), Columbine (1999), Virginia Tech (2007), the BP oil spill (2010) and now the Boston Marathon bombings all took place between April 15 and 20. For that matter, the Texas City fertilizer explosion of 1947, America’s worst industrial accident, happened on April 16. Pattern? The Oklahoma City bombing was timed to be on the anniversary of Waco, but otherwise it’s a fluke, a coincidence that the country can hope will fade away amid many peaceful Aprils to come.

The motive for the Boston bombings is still unknown. News reports are conflicting. The two brothers apparently have been in the country for years. Although they have been described as Chechens, it’s not obvious that their birth country is relevant. This may turn into a confluence of terror narratives and criminal patterns — radical ideology, alienated youth, divided families, the influence of a charismatic leader, and finally the desire for media exposure.

Two brothers, apparently, were able to kill innocent people with makeshift bombs using ordinary pressure cookers and material that might have cost only $100. Thursday night they robbed a 7-Eleven, killed an MIT campus police officer, carjacked a Mercedes SUV and tried to flee. Pending further information, this does not look like the work of a couple of criminal masterminds.

A striking feature of this week’s news has been misinformation. That’s been present with every big breaking story for many years, including 9/11, when Washingtonians heard incorrect reports of explosions at the State Department, the Capitol and the USA Today building. What was different this week was social media, which sped up the misinformation metabolism. The New York Post took the prize by putting two innocent guys on the front page, saying their picture had been circulated by authorities. The executive editor later defended the decision by saying that the paper never called them suspects. Journalistically, not an auspicious moment.

Big stories spawn mistakes. The social-media search for the Boston bombers revealed that even a crowdsourced investigation, with myriad eyeballs scanning countless images, can manage to come up with nothing but misleading or erroneous theories.

National tragedies are rarely so prolonged, so unbounded. We come to expect that, after the horror, there will be a period of mourning, an attempt at closure, perhaps a church service with remarks by the consoler in chief. But on this Friday, the story still has no ending, and more families are grieving, and no one knows how this will play out.

As they say: Developing.