Senator Chris Van Hollen of Maryland has emerged as a favorite of Democrats seeking an alternative to Senator Chuck Schumer, who says he has the votes to win.

The company said that some of its servers were unexpectedly unavailable, straining the remaining infrastructure, and that it was working to bring users back online.

At least eight people were killed and more than a dozen others injured when a three-story building in Flatbush collapsed on Wednesday, officials said.