A B737-300's leading edge devices did not extend with Flaps 1 selection on approach. An emergency was declared followed by a normal landing. The brakes overheated after landing requiring Airport Rescue and Fire Fighters to follow the aircraft to the gate then be recalled with increased smoke.

Narrative

On Approach; selected flaps 1. Trailing edge flaps came down; but no leading edge devices. Went through QRH; declared emergency with ATC; informed Flight Attendants we would make a precautionary landing. Landing uneventful. Fire equipment met the aircraft just after clearing runway; checked brakes and said they would follow us to the gate. Fire command stated they saw smoke; but no fire. Once at gate we ok'd them to leave. (big mistake) Once the cabin door opened I was hoping passengers would deplane as quickly as possible due to the hot brakes. Gate agent would not allow passengers to deplane due to customs even though the situation was explained to her regarding the hot brakes and possible fire that could occur. It wasn't until she could actually see for herself that smoke was coming from the wheels that she allowed passengers off the aircraft. Fire Department was called back to the aircraft and they agreed they should have babysat the aircraft longer because the brakes can heat up after the it is parked. No idea why the leading edge devices didn't work properly. While this event turned out successful overall; I believe that the flight crew should have had the Tower notify Customs to meet the plane so that passengers could deplane as quickly as possible. The Gate Agents should also become aware that normal procedures need to be put aside when a possible emergency exists. The thought of having to use evacuation slides to get passengers off an aircraft just because we are at a customs gate just doesn't make sense.