Context : Starbursts are one of the main contributors to the chemical enrichment of the interstellar medium .
However , mechanisms governing the interaction between the recent star formation and the surrounding gas are not fully understood .
Because of their a priori simplicity , the subgroup of H ii galaxies constitute an ideal sample to study these mechanisms .

Aims : A detailed 2D study of the central region of NGC 5253 has been performed to characterize the stellar and ionized gas structure as well as the extinction distribution , physical properties and kinematics of the ionized gas in the central \sim 210 pc \times 130 pc .

Methods : We utilized optical integral field spectroscopy ( IFS ) data obtained with FLAMES .

Results : A detailed extinction map for the ionized gas in NGC~5253 shows that the largest extinction is associated with the prominent Giant H ii region .
There is an offset of \sim 0 \aas@@fstack { \prime \prime } 5 between the peak of the optical continuum and the extinction peak in agreement with findings in the infrared .
We found that stars suffer less extinction than gas by a factor of \sim 0.33 .
The [ S ii ] \lambda 6717/ [ S ii ] \lambda 6731 map shows an electron density ( N _ { e } ) gradient declining from the peak of emission in H \alpha ( 790 cm ^ { -3 } ) outwards , while the argon line ratio traces areas with N _ { e } \sim 4200 - 6200 cm ^ { -3 } .
The area polluted with extra nitrogen , as deduced from the excess [ N ii ] \lambda 6584/H \alpha , extends up to distances of 3 \aas@@fstack { \prime \prime } 3 ( \sim 60 pc ) from the maximum pollution , which is offset by \sim 1 \aas@@fstack { \prime \prime } 5 from the peak of continuum emission .
Wolf-Rayet features are distributed in an irregular pattern over a larger area ( \sim 100 pc \times 100 pc ) and associated with young stellar clusters .
We measured He ^ { + } abundances over most of the field of view and values of He ^ { + + } /H ^ { + } \hbox { \hbox to 0.0 pt { \lower 2.365 pt \hbox { $ \sim$ } } \kern - 3.0 pt \raise 1.72 % pt \hbox { $ < $ } } 0.0005 in localized areas which do not coincide , in general , with the areas presenting W-R emission or extra nitrogen .
The line profiles are complex .
Up to three emission components were needed to reproduce them .
One of them , associated with the giant H ii region , presents supersonic widths and [ N ii ] \lambda 6584 and [ S ii ] \lambda \lambda 6717,6731 emission lines shifted up to 40 km s ^ { -1 } with respect to H \alpha .
Similarly , one of the narrow components presents offsets in the [ N ii ] \lambda 6584 line of \hbox { \hbox to 0.0 pt { \lower 2.365 pt \hbox { $ \sim$ } } \kern - 3.0 pt \raise 1.72 pt% \hbox { $ < $ } } 20 km s ^ { -1 } .
This is the first time that maps with such velocity offsets for a starburst galaxy have been presented .
The observables in the giant H ii region fit with a scenario where the two super stellar clusters ( SSCs ) produce an outflow that encounters the previously quiescent gas .
The south-west part of the FLAMES IFU field is consistent with a more evolved stage where the star clusters have already cleared out their local environment .

Conclusions :