I'm studying numbers and I found this example: На станионе собралось пятьдесят тысяч человек. the subject should be in genitive plural, If I'm not wrong. Why the verb is in past singular? Is it like in english for "people"? Thanks in advance.

I'm studying numbers and I found this example:
На стадионе собралось пятьдесят тысяч человек.

The subject is genitive plural, if I'm not wrong. 

Why is the verb in past singular? Is it like English people? 

Thanks in advance.