RAMSEY — Service on the Northstar commuter rail line was canceled Friday and Amtrak trains from North Dakota to the Twin Cities were detoured after a Burlington Northern Santa Fe train derailed and blocked the tracks between Big Lake and Ramsey.

But commuter rail service will resume Saturday, Metro Transit said. All Northstar train trips will be free on this weekend for the opening of the light-rail line connecting Minneapolis and St. Paul.

The derailment happened about 2:15 a.m. when about 16 empty BNSF freight cars jumped the tracks, said BNSF spokeswoman Amy McBeth. There were no injuries.

Metro Transit offered limited bus service from Elk River, Ramsey, Anoka, Coon Rapids and Fridley on Friday morning, but advised customers to find other transportation. Replacement buses also will be used for the evening commute home, Metro Transit said.

Customers will not be charged for replacement bus service, reports say.