According to:
http://www.cnn.com/2006/US/02/08/air...ion/index.html

It was a Cessna 182 and a 172 SG ("an experimental plane made in
Scandinavia")...

Anyone found a picture of one of these?

snip
Monica Zech, a public information officer for El Cajon Fire and Police,
said the planes were a 182 Cessna and a 172 SG, an experimental plane
made in Scandinavia.

The latter was was initially identified as a helicopter, but its tail
number revealed it later to be a fixed-wing, experimental plane, she
said. "They look kinda funky."
/snip