London police stabbed amid dauntingly complex security operation for Queen Elizabeth II's state funeral

Thousands of people from across the world are set to arrive in the United Kingdom to attend Queen Elizabeth II's state funeral service on Monday. The guest list for the service includes around 500 foreign dignitaries, including about 100 heads of state. As CBS News senior foreign correspondent Holly Williams reports, that makes it a massive security challenge. 

The U.K. has plenty of experience organizing elaborate public events, from the funeral of Princess Diana in 1997, to the royal weddings of her children that have come since.

All those events have required meticulous preparation. But this is different. The queen's funeral is reportedly bringing with it the most complex security operation London has ever undertaken.