Siren Truck?

[SiraIceshine]

So I'm in Richmond VA, and I start hearing this siren around 12 am. I go to investigate, and its a truck, rolling around the parking lot of the Kroger. It didn't have any visible siren, but the siren was definitely coming from it. No one here seems to know. I couldn't get a very good look at it, because the moment I showed up, it left. I think there was something like "Hi-Tech" on the side of it, but I googled it and can't find anything about it. It looked like a large pickup truck, with a slanted back, and what looked to be an exhaust pipe coming out of the top. Can anyone help identify this for me and explain its purpose?

[kx250rider]

Parking lot vacuum, maybe? Those things sure sound like a siren, and nearly as loud...

Charles

[SiraIceshine]

I googled it, and yes that is exactly what it was! Thanks so much.