safest place to take cover and store weapons was in hospitals and schools. That, in and of itself, is a war crime. If a hospital is used by the enemy as a base to store weapons or to engage in battle, it then becomes a legitimate target and not a war crime to bomb.

BTW, All Red Cross and MSF hospitals are mandated weapons free (armed guards are allowed at gates and periphery for security). Here's the one that the US bombed in Kabul:

MSF opens surgical hospital in Kunduz
Only trauma centre of its kind in north of country
As violent conflict continues in northern Afghanistan, Médecins Sans Frontières (MSF) has opened a 55-bed surgical hospital in Kunduz Province. The hospital, which opened on Aug. 29, provides urgent surgical care and follow-up treatment for people suffering life-threatening injuries. Fighting over the last year in Kunduz has led to large numbers of people who have sustained bomb blast, shrapnel and gunshot wounds, and who are in need of specialized surgical care.
...
In all locations where MSF is working in Afghanistan, a strict no-weapons policy is implemented to ensure patient safety and security. It is imperative that no armed people are present in medical structures. Such a presence could make the facilities targets of attack.

Bombing that hospital is definitely a war crime.
Here's a video when the terrorists mortar bombed a Russian field hospital that was just setting up to receive and treat civilians evacuating from East Aleppo. The female doctor you see being carried out later died (along with another).

Weekly World News, or maybe the National Enquirer are far more reliable sources than DKos. DKos floats down around the level of a WH press release, or an Intel assessment by John McCain, or maybe an earnest assurance by Bernie Madoff.

Most of their output is now fake news.