Why are more than 2.1 million Stork Craft cribs being recalled in the biggest crib recall in US history?

Four babies have died and 31 others have been entrapped or fallen from one of the 2.1 million Stork Craft cribs recalled. The US Consumer Product Safety Commission (CPSC) and Health Canada are aware of 110 incidents in which the drop-side of a Stork Craft crib detached. Of those, 15 were entrapments in which four children died of suffocation.

The US CPSC information is that the cribs have been recalled for:

The metal support brackets used to support the crib mattress and mattress board can crack and break. When one or more support brackets break, the mattress can collapse and create a dangerous gap between the mattress and crib rails, in which a child can become entrapped and suffocate.

See the related link section below for a link to the full safety commission report.