Two Maryland drivers died after their cars left the road and struck trees in separate weekend accidents, police said Sunday.

In the first crash, late Saturday night, Immar Enrique Serpas, 30, of Gaithersburg, was driving southbound on Montgomery Village Avenue when his car crossed over into a median and struck a tree, Rockville police said. Authorities responded to the intersection of Montgomery Village Avenue and Midcounty Highway just after 10 p.m.

Police said Serpas was pronounced dead at the scene. Why he left the roadway is still under investigation.

The second wreck occurred early Sunday in Howard County. Police said they believe that Kelly Jordon Duffy, 23, of Windsor Mill, might have fallen asleep or failed to merge into a single lane while driving north on Route 32 near Fox Chase Road at about 3:20 a.m. Duffy, who was pronounced dead at the scene, was not wearing a seat belt, police said.

Both drivers were the only people in their cars, and no one else was injured in either crash, according to police.