By Simon Watts
BBC correspondent in Alcala de Henares
The black ribbons of mourning are everywhere at the station in Alcala de Henares. Pinned on to Spanish flags, painted on rolling stock, attached to benches.
They represent the grief of a town where dozens of people left for work or school on Thursday morning, only to find themselves engulfed in Spain's worst ever terrorist attack.
The protesters headed to the station - the city's symbol of grief
At exactly noon on Friday, the platforms were empty as the station joined the rest of the country in observing 15 minutes of silence.
With the rain drizzling down, passengers, platform staff and passers-by stopped to remember the dead. Candles burned at a small shrine by the ticket-vending machine. A banner read: Life For The Killers.
'Empty and powerless'
The station's ticket collector, Andres Beltran, was in the front line of the protest.
The city's station is full of shrines to the blasts' victims
He said he still felt an "overpowering sensation of grief". He couldn't understand why "the terrorists were willing to kill just anyone - at random".
Andres Zaya, who runs the newspaper kiosk, felt himself "empty and powerless in the face of so much brutality".
Thursday was his 33rd birthday, and it was, he said, probably "the saddest of his life".
Fifteen minutes later, the silence ended with a deafening round of applause.
A train for Madrid arrived and people boarded it sombrely, their thoughts focused on an event that many still find unreal.
'We won't forget you'
At the historic Cervantes Square in the centre of Alcala de Henares, another group had gathered to mark the silence. Every building had put up a black ribbon or a poster saying Enough Is Enough.
The train service stopped so people could observe 15 minutes of silence
Groups of students draped in Spanish flags streamed away from the square, down the streets where Spain's most famous writer once lived.
Their faces were painted with slogans My Only Appeal Is For Peace, We Won't Forget You and No To ETA.
Suddenly the mood changed - the students decided to march to the station. A chant went up: Don't look At Us, Join Us.
The groups of protestors linked up and headed for the symbol of the town's mourning. Pensioners and housewives joined them, caught up in the students' energy.
Hairdressers at a salon stop work to add their voices to the chants of "murderers, murderers".
'Part of Spain'
Alejandra Dominguez and her friends from the local high school spent all morning preparing a huge banner. It read: It's Very Easy To Kill Workers And Students.
A van with detonators and a tape recording of Koranic verses was found in the city
She catches the train to Madrid every day and knows how easily she could have been a victim of the attacks.
Alejandra's group are going to Madrid later in the day to demonstrate.
Are they afraid of getting the train? "Yes, but we have to be there to express our sorrow."
Many of those who died on Thursday were immigrants from North Africa or Latin America, heading for low-paid and sometimes illegal work in the Spanish capital.
Monica Franzzuine, from Uruguay, said the response of Alcala de Henares had been extraordinary.
She said her community has been made to feel "part of Spain".
"The terrorists won't force me to leave", she said.
By the time it reached the station, the demonstration was about 1,000-strong.
There was a call for silence. The protestors fell to their knees, raising their hands to the sky in a symbol of peace.
The two minutes of silence flew by as everyone focused on the tragedy.
Then anger took over. The demonstrators swarm through the barriers to get to platform one, the platform for Madrid. Going up and down, the crowd chants: ETA Bastards, We've Lost 200 people, But We're Not Alone.
But outside the station, the scene was more sombre. Two girls of about 12 were in flood of tears as they left a banner reading Just Give Us Peace at the shrine by the ticket machine.
And on one of the benches, a teenager was weeping. His five female friends tried to console him with kisses.
When I asked them why he was so upset, the reply was: "He lost his best friend."