SAN FRANCISCO — Somewhere between the simple urgency of three-chord punk and the accessibility of pure pop, there is an emerging gray area where At the Drive-In and the Get Up Kids find their audience.

The label most often applied is "emo," for the bands' emotional subject matter and delivery. But at San Francisco's Bottom of the Hill on Thursday, the capacity crowd didn't seem to care about labels or definitions; they were happy just to witness the display of raw musical emotion.

When El Paso, Texas, five-piece At the Drive-In took the stage, it would have been easy to expect pure comedy from singer Cedric Bixler, with his giant afro and Richard Simmons T-shirt. Instead, he and his bandmates treated the packed club to a display of guitar-driven rock filled with sweeping choruses and slower interludes that filled the room with an edgy quiet as the crowd waited for the next outburst.

As they tore through numbers from their latest EP, Vaya, including "Rascuache" (RealAudio excerpt) and "198d" (RealAudio excerpt), Bixler and his bandmates — Omar Rodriguez-Lopez (guitar), Jim Ward (guitar/keyboards), Pall Hinojos (bass) and Tony Hajjar (drums) — bashed away at their instruments and the hot, heavy air around them as the audience listened intently, many bobbing their heads with their eyes closed.

At the end of several numbers, there was a startled silence between the end of one song and the beginning of the applause.

Careening around the stage, the bandmembers (all in their early 20s) weren't displaying their skill at macho posturing — they were throwing their songs to the audience with an urgency that the songs themselves seemed to require.

Bixler spent much of the show airborne, and even more time on his knees. He also hung from a ceiling beam, kicked at the wall and gesticulated at every chance, working up more of a sweat than the workout guru on his T-shirt probably ever did.

At the Drive-In fan Mike Richards, 21, of San Francisco, said that although he loves their records, live shows are what they do best.

"They transfer the same amount of energy, if not more, to the stage," he said. "You buy a record, like it, and go to the show, and then you wish it was a live record."

Headliners the Get Up Kids had a hard act to follow, but they dug in and took on the challenge with considerable energy. Their poppier, more straightforward sound was evident in the songs "Holiday" (RealAudio excerpt) and "Red Letter Day" (RealAudio excerpt), from their new LP, Something to Write Home About.

The Kansas City, Mo., five-piece had several audience members shouting requests between songs — some they played, some they didn't. The band has been touring the U.S. behind its second full-length LP for several months. Next it heads to Europe, Japan and Australia, followed by another U.S. tour.

Ashley McDaid, 22, of Oakland, Calif., was impressed with the variety of sounds at the show. "It had so many kinds of music. Get Up Kids are kind of poppy, At the Drive-In was harder and [openers] No Knife is very melodic."