Looks like one of the SpaceX Falcon 9 boosters exploded during launch (at 29 seconds in). Luckily the other 8 are designed to pick up the slack.

We watched the launch yesterday. At one point the video feed had the rocket aiming downwards and my girlfriend remarked that it appears to be burning up on it’s way back to earth. Wonder if this explosion coincided with her remarks. After the explosion you can clearly see the thrust pattern change from 9 well-organized burns to a chaos of flames.