Paul Kirby is a news correspondent for the British Broadcasting Corporation.
The man in charge of police in Paris has apologized for using tear gas against fans.
Lallement admitted failures in the security operation.
He said his "red line" was to save lives.
The fans were tear-gassed and pepper-sprayed by the police before the match.
Mr Lallement told the French Senate that it was a failure because people were pushed around or attacked.
He blamed the problem on thousands of fake tickets and said his force was not prepared for the scale of the problem.
It would have been foolish to charge at people if they had used tear gas outside the stadium. He said that attempts had been made to get supporters to move back.
The police chief insisted it was necessary for the match to start because the stadium was full, even though he was aware that families were caught up in the chaos.
In France, the UK and Spain, there was uproar over the fiasco outside the stadium.
Gérald Darmanin, the interior minister, blamed the trouble outside the stadium on ticket fraud which caused fans to turn up en masse.
The scale of fake tickets had not been taken into account. The police chief admitted that he may have been wrong in his estimate of the number of fake tickets.
Even though they arrived hours earlier, the fans fear for their safety in the crush. Local gangs from the Saint-Denis area descended on crowds after the match and stole phones and watches.
Steve Rotheram, the mayor of the city, will give evidence about the chaos to the Senate later in the day. There will be a hearing from the French Football Federation.
Fans of both clubs received an apology from Uefa last week. The European football governing body said that football fans shouldn't be put in that situation.