2 ACCIDENTS CLOG TRAFFIC ON 99: Two accidents within a half-hour of each other Saturday night disrupted traffic on northbound Highway 99 in Modesto. The first happened about 8:30 p.m. and left a big rig on its side on the freeway shoulder about 100 yards south of the Briggsmore Avenue offramp. The fuel tank dislodged, according to the California Highway Patrol Web site, and was leaking. Initial reports indicated the big rig might have been involved with another truck and some vehicles, but that couldn't be confirmed. The slow lane was expected to be closed until at least 10 p.m., though the Briggsmore offramp was open. The driver's condition was unknown. The second accident occurred about 9 p.m. two miles north of the first, near the Pelandale Avenue exit on the freeway. The CHP said one car apparently had a blowout and was facing sideways in the slow lane when it was struck by another. Two other cars might have collided trying to avoid the first wreck, the CHP said. An ambulance was called to the scene, but it was not clear how badly anyone was injured.