[Visual77]

Maybe a boomer spawned before the tank.

public Event_TankSpawn(Handle:event, const String:name[], bool:dontBroadcast)
{
	SetConVarInt(g_hBoomerLimit, 0);

	for (int i = 1; i <= MaxClients; i++)
	{
		if (IsClientInGame(i) && GetClientTeam(i) == 3 && IsPlayerAlive(i) && GetEntProp(i, Prop_Send, "m_zombieClass") == 2)
		{
			KickClient(i, "releasing boomers"); //or forceplayersuicide. it has to be one that don't spread vomit into survivors.
		}
	}
}