Azuth's Immobility

This spell locks all creatures within 20 feet of the caster as a hold person or hold monster spell for three rounds. A creature making a successful saving throw vs. spell is unaffected. The saving throw is made at -6 for 1st level or 1 Hit Die creatures. -4 for beings of 2nd level or 2 Hit Dice, and at -2 for those of 3rd level or 3 Hit Dice, unadjusted for those of 4th level or 4 Hit Dice, +2 for beings of 5th level, and so on. All affected creatures are freed instantly if the caster of the immobility touches or magically attacks any one of the held beings (or any item one is directly holding, wearing, or carrying), although the magic does, of course, give the caster one attack that automatically hits that target being.

If those other than the caster strike an affected creature, the individual creature struck is freed, but not the others affected by the spell. The caster can move out of spell range without ending the spell (and indeed this magic is usually employed to allow the caster to escape).