Picking up a broken tile to hurl at riot cops, a young man cuts himself and blood streams from his hand.
He is one of hundreds Venezuelans hurt in this month's deadly anti-government protests -- but for him, help is close by.
Through the tear gas and flying rocks, a squad of gas-masked medics comes charging. The "Green Cross" has arrived.
These student doctors joined in the protests at first. But now they stand on the sidelines, with bandages for anyone who gets hurt.
"We realized it wasn't our job to be demonstrating, but to give medical aid," says one of them, Daniella Liendo, 22, in a white helmet marked with a green cross.
"That is what we know how to do and it is much more useful."
- Grateful patient -
This month's unrest in Venezuela threatens to match that of 2014, when 43 people were killed during similar protests against leftwing President Nicolas Maduro.
That was the year student doctors from Venezuela Central University (UCV) founded the "Green Cross," or "UCV First Aid."
This time round it has new recruits from other universities too -- 120 members in total.
In single file, holding onto one another, they brave the clashes between masked protesters and security forces.
"We get together to help people," says Dana Chocron, a 22-year-old trainee doctor.
"We treat everyone who needs first aid, be they demonstrators, police or military."
Her team cleans and binds the hand of the young man, who declines to identify himself.
"I am very grateful," he says.
- Social media donations -
The medics meet early in the day to plan their deployment, dividing into three groups with different roles.
These range from basic first aid units to specialized groups based further away from the action which take the wounded to hospital if needed.
In an economic crisis that has caused shortages of basic goods, Venezuela's hospitals are desperately undersupplied.
The group gets its medical supplies from donations channeled via social media.
- Medic arrested -
Allies of the government have condemned it for helping the protesters.
One of the volunteers, Oscar Noya, was arrested on April 20 while treating demonstrators in a protest. He was freed hours later.
VTV state television presenter Pedro Carvajalino branded the medics a "paramilitary group."
UCV First Aid responded in a statement that his allegation "put at risk our voluntary work, which does not make distinctions based on political allegiance or uniform."
- Soldiering on -
The public prosecution service on Tuesday raised to 26 the number of people killed this month in clashes.
Several of those casualties were shot dead, officials said.
The opposition has accused the government of sending armed thugs to attack protesters. The government in turn accuses the opposition of fomenting unrest.
Despite such a tense atmosphere, crowds applaud the medics when they arrive at a rally.
Like the protesters, they vow to continue in spite of the danger, says one of the group's co-founders, Federica Davila.
"The affection and warmth that Venezuelans are showing us is what gives us the strength to carry on."