. >> reporter: september 5, 1972, the munich summer olympics were under way. mark spitz was going for a record seven goals. millions tuned in but ended up witnessing a tragedy that played out on televisions all over the world. members of a palestinian terrorist group disguised as athletes. nine taken hostage. captors demand, release of 234 prisoners. 24 hours after it began it ends at a german airport, then this announcement. >> they are all gone. >> reporter: experts say the outcome might have been avoided. >> the problem with munich was the lack of coordination between command, between tactical people on the ground and negotiators. >> reporter: october 23, 2002, in moscow, 50 armed chechen rebels attack take hostages and demand removal of russian troops. two and a half days later, russian authorities pump and unknown gas into a theater and storm it. 129 hostages are killed and all 39 terrorists. terrorists strike again two years later september 1, 2004 at a school. similar demands, the same tragic outcome. 1200 children and adults are taken hostage. russian