A child has a birthday party in California. It is a happy day. But a bad person comes to the party. The person has a gun. The person shoots many people. Four people die. Ten people are hurt. This happens on Saturday evening.
The police do not know the shooter. They do not know why this happens. The police are looking for the shooter. They think the shooter knows someone at the party.
The party is for a child. Now, families are very sad. The city leader says families should be happy together, not sad at the hospital. The police are still working. They want to find the shooter.