Turn my back and the tomatoes die

We went out of town this past weekend to attend a wedding.
When we came back, the tomatoes that I planted (and I planted quite a lot of them!) had died.

Sigh.

They were watered well, the temperatures were warm while we were gone … so I’ve no idea how/why.

Perhaps it’s just another indication of the need to start tomatoes inside with grow-lights, so that they are bigger by the time we transplant them.