1. Stall the guy until nightfall.
2. Before nightfall, arrange an accident where a large truck knocks over any streetlights. To distract them, set up a floodlight at the accident scene, so they don't realize how dark it is.
3. Hold a heavy metal concert nearby.
4. Send in a team of ninjas.
This works to cripple their ability to detect an attack, and then sends in very stealthy people.
If this plan is inadvisable, go to plan B:
1. Inform hostage-taker that if the hostage is hurt, I will simply hand him over to the family of the hostage.