Truce crumbles

• CNN crew sees protesters fall, some carried out on stretchers


• European diplomats are to land in Kiev to push for peace


• Ukraine's president declared a truce and the start of negotiations the night before

Are you in Ukraine? Send us your photos and experiences but please stay safe.

Kiev, Ukraine (CNN) -- A shaky truce crumbled in Kiev on Thursday morning, when gunfire erupted at Maidan, or Independence Square, which has been ground zero for anti-government protesters.

It is unclear what prompted the gunfire. But CNN crews at the scene reported that as security forces were moving away from the area, a group of protesters pursued them.

When the bullets flew, several demonstrators fell to the ground. At least three people were carried away in stretchers. It was unclear whether they were dead or wounded.

Shortly afterward, security forces appeared to withdraw, leaving the tent city once again in the hands of protesters.

Thursday's violent developments came just hours after embattled President Viktor Yanukovych announced a truce -- and opposition leaders had agreed to abide by.

Later Thursday, European foreign ministers will hold an emergency meeting in Brussels, while three of them will go to Ukraine to do diplomatic triage.

Opposition leader Vitali Klitschko, a former world-class boxer, is expected to sit down once again Thursday with Yanukovych. Their meeting Wednesday led to the truce.

No one wanted to see a repeat of Tuesday's lethal violence and chaotic clashes that left 28 dead, police and protesters alike. It was the deadliest day of protests, which began in November when Yanukovych reversed a decision to sign a trade deal with the European Union and instead turned toward Russia.

Dissatisfaction with the decision morphed into resentment of Yanukovych's closeness to Russia and an attack on his base of power. The protesters demand changes to the constitution that would hand some of it to the parliament.

The unrest has intensified after an anti-protest law went into effect. Throngs of demonstrators took to the streets to decry the law.

iReport: Protester describing bloodied people being rushed to medics

CNN's Nick Paton Walsh and Phil Black reported from Kiev, while CNN's Ben Brumfield reported and wrote from Atlanta.