GROUP BY in SOQL

Sample SOQL:

SELECT Count(Name), OwnerId From Opportunity Where OwnerId in ('005A0000002U5TcIAK',
'005A0000002U5U1IAK', '005A0000002U5ULIA0') and StageName in ('Active - Low Probability','Active - Med. Probability','Active - High Probability','Active - Commit') GROUP BY OwnerId