Deleting CloudFormation Stacks using a shell script

I am writing a shell script to delete a handful stacks using the cli command "aws cloudformation delete-stack --stack-name <stack1>".

When I try to delete the stacks one after the other, only the first one gets deleted and ignores the subsequent stacks. This behavior is precisely same as the management console.

I tried to run each command as a background process in the shell script but the result is still the same. When I delete the stacks one after the other in command prompt it worked fine.

Any thoughts/pointers are appreciated.