The Washington Post has spent years tracking how many children have been exposed to gun violence during school hours since the Columbine High massacre in 1999.

Beyond the dead and wounded, children who witness the violence or cower behind locked doors to hide from it can be profoundly traumatized.

The federal government does not track school shootings, so The Post pieced together its numbers from news articles, open-source databases, law enforcement reports and calls to schools and police departments.

While school shootings remain rare, there were more in 2021 — 42 — than in any year since at least 1999. So far this year, there have been at least 24 acts of gun violence on K-12 campuses during the school day.

The count now stands at more than 311,000 children at 331 schools.

If the Russians could seize the seat of power in Ukraine, or at least cause the government to flee in panic, the defense of the country would quickly unravel. Moscow could install a puppet government.

That was the Kremlin’s plan.

Instead, what transpired in and around Kyiv in the ensuing 36 days would represent the biggest foreign blunder in the 22-year rule of Russian President Vladimir Putin. His assault on the city instantly reordered the security architecture of Europe against Moscow and isolated his nation to a degree unseen since the Cold War. To the surprise of the world, the offensive against the Ukrainian capital would end in a humiliating retreat, which would expose deep systemic problems in a Russian military he had spent billions to rebuild.

Ukrainian forces lacked sufficient weaponry, ammunition and communications equipment. But what they did possess was a profound will to fight — one that would extend beyond Ukrainian soldiers to ordinary civilians and, most important, to the president himself.

Those fighting to save Kyiv also benefited greatly from key miscalculations by the Kremlin, which set in motion a plan to invade Kyiv based on poor assumptions about the mettle of the Ukrainian military, the durability of the Zelensky government and the determination of the Ukrainian people to resist. In the end, the Russians wouldn’t take any territory inside Kyiv’s city limits, instead remaining stuck for weeks on the capital’s periphery before their retreat.

The Kremlin did not respond to requests for comment.

A Ukrainian drone hit the headquarters of Russia’s Black Sea fleet in Crimea this weekend, the latest assault on a region Moscow once considered an impregnable fortress.

Plumes of smoke were seen rising from the Sevastopol military base on Saturday morning, and city residents were urged to stay at home immediately after the strike, the latest in a string of high-profile attacks on sensitive targets there and inside Russia.

The governor of Sevastopol, Mikhail Razvozhaev, said there were no casualties, and initially claimed the drone flew into the airbase’s roof after troops stationed there were not able to shoot it down. He later said soldiers had been able to target the drone, and that it had fallen onto the airbase roof after being hit. “Clarification: the drone was hit...right above the fleet headquarters. It fell on the roof and caught fire. The attack failed. Well done boys,” he wrote.

Worried locals responded to Razvozhaev by asking how a drone had slipped through air defences that at the start of the war were considered among the most sophisticated in the world. “Was our air defence system on a lunch break?” asked one. “When will you finally close the city?” asked another, suggesting the attacks were the work of pro-Ukraine partisans in the peninsula. “We fought harder against the coronavirus! There were checkposts everywhere then, now anyone and everyone enters!!!!”

ZAPORIZHZHIA, Ukraine — Russia has allegedly told workers at the Zaporizhzhia nuclear power plant not to show up to work Friday, Ukrainian military intelligence has exclusively confirmed to NBC News.

This comes amid allegations and speculation from both Russia and Ukraine that an incident is being planned Friday at the plant.

Earlier Thursday, the Russian Defense Ministry accused Ukraine and what it called its “U.S. handlers” of trying to stage a “minor accident” at the plant in southern Ukraine on Friday in order to blame Russia.

It said the “provocation” was timed to coincide with a visit to Ukraine by United Nations Secretary General Antonio Guterres and that it may involve a radiation leak.