Sanaa, Yemen (CNN) -- Clashes resumed in southwestern Yemen Thursday night after fierce government attacks against opposition posts that lasted more than seven hours in the earlier in the day.
The fighting resulted in the death of a child and the wounding of 11 others.
The child, Sameer al-Dubaee, was killed after being shot while walking in Taiz during the late afternoon.
Opposition fighters claimed they injured four troops during the clashes. The Defense Ministry said that three soldiers were injured in fighting against opposition gunmen.
Witnesses said troops had been stationed inside Al-Thawra Hospital and at least 22 checkpoints on the main roads.
Dozens of tanks and armored vehicles re-entered Taiz after being moved out Wednesday.
A senior security official in Taiz said the return of the tanks was not a sign of war but rather to assure the safety of the residents.
"The tanks will not be used against the people. They are stationed in main roads and at checkpoints to stop opposition fighters from attacking civilians," said the official, who was not authorized to talk to media.
Government and opposition forces reached a cease-fire agreement earlier this week in Taiz. Ameen Sami, a member of the peacekeeping committee, admitted that a gunmen attacked a soldier, but said that did not give soldiers the right to continue the heavy bombardment of targets in Taiz for long hours.
Medical sources in Taiz said a pregnant mother died after she failed to reach a hospital to give birth. She was delayed at a new checkpoint that government troops created, they said. CNN was able to verify the information from independent sources.
Amid the turmoil, the U.N. envoy to Yemen, Jamal Benomar, arrived Thursday morning in an effort to persuade President Ali Abdullah Saleh to sign a power-transfer proposal.
Upon arrival, Benomar said, "My visit is to follow up on the political efforts to rid Yemen from the current crisis."
During the day, tens of thousands of youth marched the streets of Taiz calling for a regime change.
Sanaa was the site of the largest march, with an estimated 200,000 joining in a three-hour trek around the capital.
"We march with roses in our hands and hand them over to the soldiers who are directing their weapons in our direction," said Mansoor al-Hamati, a youth activist in Sanaa.
"Gradually, we will convince our soldiers that they are one of us and the regime is oppressing them as well," Hamati added.