A winter storm expected to dump 5 to 9 inches on the Ann Arbor area arrived earlier than expected and has already caused one fatal crash on I-94 in Ypsilanti and numerous other crashes, police said.

All lanes of eastbound I-94 are closed because of the crash.

Some school districts, including Ann Arbor Public Schools have canceled after-school and evening activities. Ann Arbor school officials have made no decision about classes Wednesday, spokeswoman Liz Margolis said. "We're assessing all day. Normally we don't make (a decision) until the morning, but it just depends on conditions," she said

Snow started falling about 7 a.m. as crews for the Washtenaw Road Commission were starting their shift, said Jim Harman, director of field operations. The Road Commission has its full fleet of 46 plow trucks working to keep roads clear, Harmon said.

"We're just asking people to slow down ... and give our drivers plenty of space to do their jobs," said Harmon, noting that drivers will likely work overtime today. "And we expect to be calling them in early tomorrow and expect them to be working an extended work day tomorrow."

In the City of Ann Arbor, 11 trucks are out salting and plowing, said Kirk Pennington, field operations supervisor.

The forecast originally called for the storm to begin about 10 a.m. "The system was moving a little faster than we originally planned," said Rachel Kulik, meteorologist with the National Weather Service in White Lake. "We're expecting it to come a little bit earlier and snow moderately throughout the day."

Kulik said meteorologists are no longer predicting the period of heavy snow from 6 p.m. to midnight that was in the original forecast. Instead, snow will be steady throughout the storm.

The weather service has issued a winter storm warning through 10 a.m. Wednesday morning. Winds gusting to 30 mph Wednesday could cause blowing and drifting snow Wednesday, Kulik said.

The storm will affect all of southeast lower Michigan, but areas north of the M-59 corridor will get less snow than those to the south.