Three hours of darkness:
1. “Now from the sixth hour there occurred darkness over all the land until the ninth hour”, Matthew 27:45.
2. “Now when the sixth hour had come, it became dark over all the land until the ninth hour,” Mark 15:33.
3. “It was now about the sixth hour, and darkness came over all the land until the ninth hour, the sun failing” (Luke 23:44-45).
And IIRC the hours were counted starting at 6am, so the 6th hour would correspond to noon, and the ninth hour would be 3pm.
Thank you.
They certainly agree on the time.