An attack on an SDF checkpoint killed oil workers in Syria on February 21. Disputed numbers of casualties were heard throughout the day.
“Other locals are reporting different numbers, but the high is currently at 40 and the low is 16. No matter the end number it’s still big.”
One sources notes “a suicide attack has been carried out against a vehicle carrying SDF soldiers near al-Omar base. Number of casualties not confirmed, but significant. Al-Omar is a main rear base for the operation against ISIS & hosts the press pack as well as an SDF academy.”
A third report notes that: “A car bomb on Thursday killed 20 people including 14 oil workers near a base used by US-backed forces battling the ISIS group in east Syria, a war monitor said.

The full details are still unclear.